|— Genos's tagline|
Genos (ジェノス, Jenosu) is the deuteragonist of One-Punch Man. He is a 19-year-old cyborg and the disciple of Saitama. He is always aiming to become more powerful and he fights for justice. Under the Hero Association, he is given the name Demon Cyborg (鬼サイボーグ, Oni Saibōgu) and is currently S-Class Rank 14.
Genos is a mechanical cyborg of average human height. His face and ears look like that of a normal human, made of artificial skin material, and his eyes have black sclera with yellow irises. He has spiky blond hair and his eyebrows are blond (brown in the anime). He also has pierced ears. Genos's wardrobe consists of street clothes with all of his upper-body attire being sleeveless as to allow his arms to transform without hassle. He has many different sets of arms, with varying abilities and strengths. Notable examples of his various "arms" are those he used in his sparring match against Saitama and the arms he equipped to combat the meteor. Sometimes the arm sets he uses create a metal framing around his face, like when utilizing Arms Mode and in his Monster Association Arc Upgrade.
During his fight against the Forest King, he has an upgraded body, which exposes the energy core in his chest.
Genos is an extremely serious character, rarely if ever making jokes. He constantly strives to become stronger and frequently looks to Saitama for advice to achieve his goals. Since becoming Saitama's disciple, Genos is very reverent and protective towards Saitama (who he refers to as "master"). Genos envies and reveres Saitama, although this does not stop him from expressing annoyance and disbelief at the mundane training regimen Saitama used to gain his powers.
On occasion, Genos acts as a comic foil to Saitama's clueless antics, using a variety of special techniques, battle tactics and robotic upgrades to combat villains (often sustaining terrible damage in the process), only to be outclassed by Saitama with a single punch. Due to Saitama's incredible strength, Genos believes that there is a secret to Saitama's power. He is motivated to observe Saitama closely in order to understand the secret to his master's incredible strength.
Genos is an intense person, unyielding in his pursuits. Before meeting Saitama, he was even more intense but Saitama has been a moderating influence on Genos, helping him to be calmer and take a more measured approach to his pursuit of justice and power. Genos realises how far he's come when he witnesses Sweet Mask dispatch a group of alien prisoners without mercy and remarks how similarly hard-hearted he used to be himself. Genos has slowly become less serious and becomes a bit curious about some minor things such as the meaning of fun.
Genos fully respects two people Saitama, and Dr. Kuseno (the man who saved him). He extends professional respect to those who demonstrate genuine expertise, like Bang and Bomb, and tolerates people who Saitama willingly spends time with, like King. He is rather disrespectful to almost anyone else, especially those who attempt to interrupt, or pester Saitama. Whenever Bang or Fubuki command him or attempt to recruit Saitama, Genos will cut them off and tell them to get to the point. He will defend his position as Saitama's disciple, actively discouraging Saitama from letting other people get too close. This hostile behavior does not only extend to those who offend Saitama, but Dr. Kuseno as well. Genos has even called out Saitama when he called Dr. Kuseno an old man, but he immediately apologized when his master told him to give it a rest. He also does not respect the authority of the Hero Association very much, telling Sitch that even though he wasn't part of the main task force team to invade the Monster Association that he would have gone anyway, and states that none of his decisions have anything to do with the Hero Association.
Genos appears to take a certain pride in his abilities and himself. In his battle against Awakened Cockroach when he is aggravated that he had to use his instant adhesive gel, as it forces Genos to accept there were monsters faster than him. Nevertheless, his fights with G4, Face Ripper, Awakened Cockroach, and Garou demonstrate that he does not solely think about raw power and is willing to fight strategically if need be.
Genos was also a serious person before he became a cyborg, being described by ONE as having been a diligent, responsible boy from the start.
Abilities and Powers
As an S-Class hero, Genos is undoubtedly a powerful fighter. And for someone his age, Genos has a significant amount of battle experience, as he claims to have defeated countless evil entities and organizations before meeting Saitama. His youth and impulsiveness still overcome him on occasion, which sometimes costs him victory in battle. According to Gyoro Gyoro, his functionality is terrifyingly proficient but lacks the firepower to take down something big and durable as Elder Centipede. He has become more powerful since that fight and is increasingly open to fighting strategically in order to win. The Virtual Genocide System's (VGS) simulations showed Genos (at the time) with a 70% chance of victory against any disaster level demon monster.
Immense Strength: Enhanced by his cyborg physiology, Genos possesses incredible physical strength, and is capable of breaking apart the ground with a dropkick, and punching rapidly with enough force to tear apart a cliff face. He is also able to lift a truck with a single hand without difficulty. During his brief fight with the Deep Sea King, he was able to land a full-force punch on the creature that sent it flying through the wall of the safety shelter. In his fight with Garou, Garou noted that his strength rivaled that of Tanktop Master.
Immense Speed and Reflexes: Genos is very agile and he can move so fast that he appears to be teleporting. He was able to keep up with Speed-o'-Sound Sonic for a considerable amount of time in their battle, with both of them moving faster than sound.
Immense Endurance: He can continue fighting without much drawback even with only a single arm. During separate battles, he is able to stand on his feet after several blows from Carnage Kabuto, and he also able to stay conscious even after he used almost all the energy in his core. Due to most of his body being artificial, he appears to have an extremely high tolerance to injuries due to him not being able to feel pain for the most part. However, given the expression on his face after making contact with the Deep Sea King's acid spit, it could be assumed that he feels pain from the direct acidic corrosion of his body. Besides this, he does not often show significant signs of physical stress.
Full-body Cyborg Enhancement: Genos's entire body has been replaced with combat-ready cybernetics and prostheses, giving him an extreme level of strength and speed, as well as advanced sensors and projectile attacks. All of his parts have made Genos too heavy to swim and he needs special parts in order to do so. In addition to these modifications, Dr. Kuseno gave Genos the ability to taste and made it so his cybernetic body turns organic intake into biofuel, presumably to power his person. He has been shown eating on multiple occasions like when he engages in an eating contest with Saitama and when he eats hotpot at Saitama's apartment.
Core (コア, Koa): Genos's body is powered by an energy sphere labeled "CORE." It is attached to his body by a single cable and is held inside his chest. During his attempt to destroy the meteor, Genos removed the core from his chest and placed it in a similar holding place in his arm, in Arms Mode, to direct all the energy into his Incineration Cannons. During his fight with Psykos and Orochi, it transpires that the core is a nuclear reactor.
Armor and Replacement Parts: Genos benefits from the nature of robotic equipment itself. He can lose limbs or have his body torn apart, only to return in perfect or even an improved condition through replacement parts and repairs. As a cyborg, Genos does not seem to feel pain to the same extent as regular humans and can keep fighting even when limbs are severed or he is severely injured. Genos's durability is high enough that despite taking several powerful blows from Carnage Kabuto and having one of his own powerful blasts reflected at him, he was still conscious and able to stand and walk.
Cyborg Leg (サイボーグレッグ, Saibōgureggu): Genos's legs have a durable design to support high-speed movement. They are equipped with a shock-absorbing mechanism that keeps the interval between landing and the next movement short. And from his Post-Super-Fight-Arc Upgrade onward, Genos has rocket boosters installed in his legs which allow him to perform powerful kinetic kick attacks, an example of this is his Jet Drive Arrow.
Incineration Cannons (焼却砲, Shōkyaku-hō): Genos's palms contain ports that allow him to fire large, powerful blasts of heat, fire, or plasma across significant distances. One blast was powerful enough to obliterate the multi-story above-ground headquarters of the House of Evolution, as well as the top of the mountain it was situated on and a large chunk of a mountain far in the distance behind the building. His Incineration Cannons have varying levels of power depending on what set of arms he is currently using. For example, when utilizing Arms Mode, Genos's arms can produce even stronger blasts. When using his Arms for Chores he can reduce the power of his blasts to a warm breeze to dry dishes.
Hyper Sensors (ハイパーセンサー, Haipāsensā): Genos's cyborg body contains several passive and active sensors which allow him to scan the environment for enemies, both during active combat and while scouting from a distance. The sensors are not perfect, however, as they can still be confused by the extreme speed of an opponent like Saitama or by certain monsters like Elder Centipede who are so large that Genos's sensors identify it as many different enemies. And their usefulness is limited by Genos's reaction time.
Search Eye (サーチアイ, Sāchiai): Genos is capable of detecting heat signatures, analyzing speeds, and levels of energy nearby.
Instant Adhesive Gel: A tool Genos gained after his fight with Sonic to deal with opponents faster than him. The gel is extremely sticky and fast-acting, preventing fast opponents from moving and allowing Genos to defeat them.
Detachable Body Parts: Genos first sported detachable and recallable arms during his fight with G4, where the arms were retrieved with a cable. During his fight with Garou, his hands are upgraded to be able to detach from his body with ease and are armed with rocket boosters to be controlled by Genos remotely. It is also armed with steel wire to restrain opponents. Genos also reattached his torso with his lower body when he was cut in two during his battle against Elder Centipede.
Arm-Blades: Genos's arms are armed with razor-sharp blades. These debuted in his Post-Super-Fight-Arc Upgrade. He used them to kill a number of low ranking members of the Monster Association sent to assist Garou as well as to blind Elder Centipede during their fight, to seemingly no avail.
Boosters (ブースター, Būsutā): Once engaged, these boosters located in his shoulders and elbows enable amazing acceleration and limited flight. Using his palms for jet propulsion in the opposite direction, Genos can perform rapid maneuvers. The upgrades given to Genos by Dr. Kuseno before the Monster Association raid have given these boosters greater power, granting Genos the ability to travel upwards at great heights.
Arms for Chores: When not in battle, Genos can change into special arms dedicated to house chores. His right hand comes with a built-in vegetable peeler and his palms also allow him to generate a warm breeze to dry dishes. It was also commented that Genos could be the number one housekeeper.
List of Upgrades
Anti-Saitama Tactical Arms: These are a set of replacements Genos used during the National Superhero Registry Arc when Genos and Saitama sparred in the quarry. These arms are differentiated from his normal arms by being black, having much larger shoulders, forearms, and fists and generating an orange glow between the plates of metal. The fists and forearms of these arms open to reveal several cannons. The beams generated by the cannons are significantly larger than those of his normal arms and are characterized by smaller individual beams circling the main beam. If he puts both of his fists together the resulting blast is massive, much larger than that of one arm.
Arms Mode (アームズモード, Āmuzu Mōdo): A prototype weapon system. When inactive, it takes the form of a suitcase. To activate it, Genos pushes a button on the handle and then throws it in front of him. The suitcase splits down the middle and separates, each half then opening to reveal the "arms" inside. The arms then clasp over Genos's arms. When the "arms" fully attach, parts run up his shoulders and neck and his face is framed by pieces of metal. The new arms are much thicker and are all black, with the blaster on his palm having changed shape as well. While using these arms, Genos was shown to be able to move his core to the bicep of his left arm, directing all of his power into a massive blast. Arms Mode bares a striking resemblance to Genos's Anti-Saitama Tactical Arms, possibly alluding to the former being an upgraded version of the latter.
Post-Sea-Monster-Arc Upgrade: After his battle against Deep Sea King, Genos now has the ability to detach his limbs, namely his hands, as seen in his fight against G4 when he used Rocket Punch. His limbs are only semi-detachable as they are still connected to the main body via a cable. According to the Virtual Genocide System's (VGS) simulations, with this upgrade Genos would be able to defeat Mosquito Girl and Deep Sea King even in his wet form with relative ease. However, the Virtual Genocide System's (VGS) simulations also show that Normal Carnage Kabuto would still beat Genos in two attacks even with the upgrade.
G4 Upgrade: After defeating the battle robot G4, Genos replaces his parts with the parts of G4 which enhanced his speed and power. This enables him to keep up with Speed-o'-Sound Sonic, and even cut off his hair. After this upgrade the design of Genos's arms changes again. His shoulders are larger than previous upgrades with two pieces of shoulder armor on top of one another both with holes in them to allow heat to escape and slot drive screw-like joints for his shoulders to move. His arms appear as if they are wrapped in metal tape with rivets all along them going down to his wrists and he has the same slot drive screw-like joints on his elbows. His hair also received fiber enhancements to make his hair resistant to shock and heat. Moreover, he is equipped with adhesive gel.
Post-Super-Fight-Arc Upgrade: After Genos's body was destroyed by Gouketsu, Dr. Kuseno rebuilds him into a new version that further increases his strength. With these upgrades, he was able to keep up with the "Hero Hunter" Garou who complimented his abilities and even compared his physical strength to that of Tanktop Master. Furthermore, Genos can now recall his body parts if they get detached. Additionally, he can summon blades from his arms that he used to slice through a horde of Wolf/Tiger level monsters during the battle against Garou. He used these against Elder Centipede's exposed face later. His arms also have an almost net-like ability that he used to bind Garou to a tree after his arm was ripped off.
Monster Association Arc Upgrade: After Genos's battle against Elder Centipede, Dr. Kuseno upgraded Genos once again to a new form. This form has sharper and more jagged arms than his previous forms with 3 large protrusions on each shoulder resembling knives, in this upgrade he takes on an almost demon-like appearance. Additionally, the blaster ports in his palms take the form of gaping demon mouths and there are what appear to be tubes or wires coming from each of his arms connecting to the back of his head, forming a metal framing around his face. What sets this upgrade apart from others even further is its full black appearance, compared to previous upgrades that were a mix of black and other colored metals, or no black at all. The armor is also arranged as overlapping plates rather than plates that abut one another. This form is unbalanced and focuses heavily on raw destructive power, at the request of Genos, because of Saitama's suggestions. Dr. Kuseno stated that Genos can only go full-power with this new upgrade for 10 seconds. Any more and his core would possibly give out and explode, killing Genos. In this form, Genos has beam emitters integrated along his arms & shoulders that he can use to attack enemies around him while he is otherwise occupied. These beams bend and arc towards his enemies similar to those of G4, indicating that Dr. Kuseno integrated the technology into this upgrade. At full power, stated by himself, Genos is capable of firing energy beams powerful enough to destroy a giant meteor in one shot. With this, he managed to deflect the fusion of Psykos and Orochi's energy attacks with his own. With his ten-second last resort attack, True Spiral Incineration Cannon, Genos was even able to match and completely negate one of the fusion monster's largest energy beams using said attack. The heat generated by the attack melted the armor over his core and left his arms glowing white-hot.
Post-Psychic-Sisters-Arc Upgrade: At some point after the final battle with Monster Association, Genos received another upgrade from Dr. Kuseno. His appearance in this form bares a resemblance to his G4 Upgrade in the manga, with the addition of bracers on his forearms and core visible on his chest. Genos gains two new abilities with this upgrade called Lightning Core and Scorching Core respectively. The first of which produces an extremely bright, blinding light from the core in his chest and second of which produces extreme heat from his core able to deal damage in a large area at the cost of damaging himself. We are not shown any further features of his Lightning Core ability, if any exist, as Genos cut his spar with Saitama short before they even started trading blows. Genos claims that in this form he has enough firepower to fight Dragon-level threats. This is later proven correct when he is able to defeat the Dragon-level threat, The Extended Family of Darkness, by himself, though sustaining significant damage in the process. Furthermore, in a previous battle, he still had some difficulty fighting a Demon-level monster, losing one of his arms and taking minor damage to the rest of his body during the battle despite winning. Additionally, his speed has increased considerably, as seen when he briefly kept up with Flashy Flash in a short fight with him outside of Saitama's new apartment in A-City. Additionally, when he fought the Internet Surfers he was able to dispatch one of the monsters at roughly the same speed as Flashy Flash.
Post-Supreme-Hero-Arc Upgrade: After sustaining heavy damage in his fight against the Extended Family of Darkness, Genos is once again repaired and upgraded with new parts courtesy of Dr. Kuseno. This new form has the same exposed chest core as his previous upgrade with triple-layered pauldrons on his shoulders, similar bracers to his previous form with plates on the front and two sets of rivets in them on each side, his biceps have two large bolts going all the way through from one side to the other. He also has a large metal collar around his neck with rivets lining both sides of his neck up to below his ears. In this form, with apparent little effort, he was able to defeat a Dragon-level threat alongside Drive Knight fairly easily and with no sustained damage. Upon releasing the full power state of the upgrade, which only lasts about 30 seconds, Genos was capable of engaging in combat with three Dragon-level threats Machine God Body, Machine God Ray and Machine God Tech simultaneously, even managing to quickly destroy all of them singlehandedly, albeit only 9% of his energy remained after the battle.
Final Secret Upgrade: Before passing away, Dr. Kuseno revealed the final set of upgrades he'd prepared for Genos as a secret weapon. According to the doctor, it is equipped with Genos' newest system upgrades and therefore is extremely powerful.
Expert Hand-to-Hand Combatant: Thanks to his cyborg physiology and experience, Genos is one of the most proficient fighters in the series. Genos can utilize his various enhancements to distract opponents and calculate how powerful they are, as well the exact amount of power he'll need for battle and, as the series goes on, Genos improves his skills and capabilities as a cyborg. He makes use of a large variety of weaponry and upgrades in battle and is a very capable fighter in both close quarters and long-range fighting. He is skilled enough in hand-to-hand combat to fight the likes of Speed-o'-Sound Sonic and Deep Sea King, even at a disadvantage, he could fight on par with the latter for a short time despite having just one arm. However, he's still not a match for other extremely skilled fighters such as Bang or Garou.
- Incineration Cannon (焼却砲, Shōkyaku-hō): Genos launches a concentrated beam of fire to rapidly heat up a target to the point of being able to melt various metals. It was first used against Mosquito Girl.
- Maximum Gauge Incineration Cannon (最大出力焼却砲, Saidai Shutsuryoku Shōkyaku-hō): A variation of Incineration Cannon where Genos uses more energy than usual. It was first used against Saitama.
- Super Incineration Cannon (超焼却砲, Chō Shōkyaku-hō): 
- Spiral Incineration Cannon (螺旋焼却砲, Rasen Shōkyaku-hō): An improved version of Genos's Incineration Cannon with the upgraded version of Genos's original incineration cannons received after the Super Fight Arc. It was first used against Phoenix Man but is blocked by Elder Centipede. The attack is strong enough to damage Senior Centipede's carapace.
- Super Spiral Incineration Cannon (超螺旋焼却砲, Chō Rasen Shōkyaku-hō): A variation of Spiral Incineration Cannon where Genos uses more energy than usual by firing the incinerating blast directly from the core. First used against Elder Centipede. The attack was capable of burning Elder Centipede's insides, making him molt, though it wasn't sufficient enough to permanently end Elder Centipede's life.
- True Spiral Incineration Cannon (真螺旋焼却砲, Shin Rasen Shōkyaku-hō): A variation of Spiral Incineration Cannon when Genos is utilizing his ten second time limit. The blast was capable of matching and completely negating one of the strongest energy attacks from the fusion of Psykos and Orochi. However, this was a one-use attack and Genos was overheating dangerously after using it.
- Self-Destruction (自爆, Jibaku): If there is no chance in winning in combat, Genos can destroy himself and hopefully his opponent by overheating his core. He first attempted to use it during his fight against Mosquito Girl, but stopped after Saitama interfered. When his core started thermal runaway after his fight with Psykos and Orochi, he asked the other heroes to evacuate to a 5km distance as he would explode and take all the remaining monsters with him. However, Fubuki was able to cool the core down using her telekinesis, enabling him to regain control of it.
- Machine Gun Blow (マシンガンブロー, Mashingan Burō): Genos throws a chain of fast punches. It is strong enough to shatter a cliff face. It was first used against Carnage Kabuto.
- Heat Machine Gun Blow (ヒートマシンガンブロー, Hīto Mashingan Burō):  A variation of his Machine Gun Blow where his fists are heated to extreme temperatures.
- Heavy Machine Gun Blow (ヘビーマシンガンブロー, Hebī Mashingan Burō): A variation of his Machine Gun Blow where his punches are delivered with much greater power and speed than normal.
- Lightning Eye (雷光眼, Raikōgan): (Anime-only) Genos uses his eye to produce a blinding flash of light. It was first used against the Deep Sea King.
- Boost Attack (ブーストアタツク, Būsuto Atakku): After using his left arm for jet propulsion in the opposite direction, Genos maneuvers towards his opponent and hits them with a strong kick from his left leg. It was first used against the Deep Sea King.
- Rocket Punch (ロケットパンチ, Roketto Panchi): Genos's forearm is retractable due to a cable connected to his elbow, which gives this attack great range. Genos punches at his opponent with extreme force with the aid of boosters inside his lower arm and, after the punch, his arm retracts back to its previous state. It was first used against G4.
- High Voltage Fist (ハイボルテージフィスト, Hai Borutēji Fisuto): Genos chokes his opponent with a powerful, electricity imbued hand and shocks them with it.
- Rocket Stomp (ロケットストンプ, Roketto Sutonpu): Genos leaps up above his opponent and then propels himself downwards with the rocket boosters on his back to stomp them into the ground.
- Dual Blade Rush (デュアルブレードラッシュ, Dyuaru Burēdo Rasshu): Genos jumps in the air, equips both arm blades and rushes towards the target with his rocket boosters and proceeds to stab the opponent rapidly. It was first used against Elder Centipede when Genos tried to fight him alone.
- Jet Drive Arrow (ジェットドライブアロー, Jetto Doraibu Arō): Genos uses the rocket boosters on his shoulders and legs at full power to deliver a powerful kinetic kick, the boosters on his right leg form the shape of an arrowhead. It is strong enough to break one of Elder Centipede's teeth and completely destroy G5's true form, causing it to explode violently.
- Arm Lasers: Genos has numerous beam emitters integrated along his hands, arms, and shoulders. These rays seemingly bend and arc at his whim similarly to those of G4, indicating that Dr. Kuseno integrated the technology into his latest upgrade. He used these lasers to destroy the leftover goo from Orochi's body that was still in search of blood on the surface.
- Lightning Drill Cannon (穿天雷光砲, Senten Raikō-hō, Viz: Piercing Lightning Cannon): Genos unleashes his full power, launches incredibly powerful beams of energy that were able to deflect and briefly contend with the fusion of Psykos and Orochi's energy attacks. According to himself, these energy beams are also powerful enough to destroy a giant meteor in one shot.
Tactical Combination: Promoted Rook (戦術合体: 龍王, Senjutsu Gattai: Ryūō, Viz: Tactical Combination: Dragon King): Genos was sufficiently compatible with Drive Knight to complete a Tactical Combination with him. Genos and Drive Knight, utilizing Drive Knight's shape-changing box, transforms into a large humanoid robot with several large thrusters and heavy armor. Genos is positioned where the head would be while Drive Knight is embedded within the chest-plates. The transformation's main weapon of choice is a giant sword with a guard shaped like a dragon's head and wings.
- Lightning Core (雷光核, Raikō Kaku): Genos uses his core to produce a blinding flash of light. It was used during the second sparring match between Saitama and Genos.
- High Voltage Tackle (ハイボルテージタックル, Hai Borutēji Takkuru): Using his Lightning Core, he imbues his body with electricity and tackles his opponent.
- Scorching Core (焦熱核, Shōnetsu Kaku): Genos uses his core to produce heat. It was used in his fight with the Extended Family of Darkness, being able to incinerate the group of monsters at the cost of damaging Genos's own body.
- Floating Core (浮空核, Ukisora Kaku): Genos is capable of using his core to levitate in the air, granting him greater maneuverability against his opponents.
- Super Magnetic Core (超磁核, Chōji Kaku): Genos uses his core as a magnetic conductor to gather the metal around him. He is capable of drawing metal objects together to form a giant arm, which he uses to attack Machine God Body.
- Freezing Core (凍結核, Tōketsu Kaku): Genos uses his core to generate ice, which is capable of freezing his opponents instantly.
- Roaring Dragon Core (龍鳴核, Ryūmei Kaku): Genos dramatically increases the energy output of his core, boosting his abilities for thirty seconds. With this increase in power, Genos was capable of defeating all three Machine Gods.
Notebook: Genos always carries with him an acid-proof notebook to write down notes.
- (Genos telling Saitama his history) "It all started 4 years ago. I was 15 years old and still a normal human being. Even in this harsh world, I had a pretty happy and peaceful life with my family until then. But one day, a crazy cyborg attacked our town all of a sudden. He had completely lost his mind. I guess his brain had been damaged during its transplantation into his cyborg body. He left after destroying everything in the town. The parks, the schools, the buildings, my home. Of course, my family didn't survive. Only I was miraculously spared, but as I was just a meek 15-year-old boy back then, I wouldn't have survived long all alone in the ruins of a town if Dr. Kuseno hadn't passed the town by chance and found me. Dr. Kuseno is a scientist of justice and was pursuing the cyborg to stop him. I begged Dr. Kuseno to transform me into a cyborg and was reborn as a cyborg who fights for justice. I made a promise to Dr. Kuseno to find that cyborg one day and destroy him."
- "I am willing to do anything to become more powerful. However, I can't picture myself coming even close to attaining teacher's power."
- (Referring to Saitama) "If there was a threat that my master could not defeat, humanity would have perished long ago."
- (Referring to Sweet Mask) "He reminds me of myself before I met sensei. There is no mercy in his heart. A strong hatred for everything evil, eager to eliminate them all."
- (To G4) "Your target may be King, but I know a man who's even stronger than him. And I am stronger than you."
- "Using sheer numbers to compensate the lack in strength of each individual, that kind of wishful thinking will get one killed one day."
- (Referring to Saitama) "No monster is a match for him. He is the strongest hero"
- (Referring to G5) "Looks like an upgraded version compared to last time. Still, it seems I'm upgrading at a faster rate."
- (Struggling against the fusion of Psykos and Orochi) "Such power... It's taking my all just to deflect it away! It's barely been five minutes since I arrived, and I have already been forced to use my last-resort weapon, capable of destroying a giant meteor in one-shot!"
- Genos is ranked 4th in the popularity poll.
- When designing Genos, Murata tried pairing him with Kaneda's jacket from Akira and even referenced Tetsuo's appearance. Looking back, he thinks those early sketches were so "over the top."
- According to the databook:
- What he likes are Saitama's teachings and oiled sardine.
- What he dislikes are people who look down on Saitama and complicated electronics.
- His hobbies are surfing the internet, reading, and writing in his diary.
- Genos is the first new S-Class hero in 2 years however this is contradicted in Weapon where Metal Bat is promoted to S-Class one year ago.
- The origin of his hero name comes from his aggressive attacks without being afraid of any vicious monsters or disasters.
- Genos's signature move, Machine Gun Blow, may be a reference to Street Fighter, in which the Machine Gun Blow is one of Dudley's special moves.
- Only one week after he joined the Hero Association, Genos was ranked #6 in popularity by the public and in the Top 5 most handsome heroes.
- Murata once drew Genos as a female.
- ONE has said that Genos is rather powerful even among the S-Class heroes.
- Genos's tears are made of oil.
- Despite every part of him besides his human brain becoming mechanized, Genos still has the ability to eat. He attributed this to Dr. Kuseno wanting him to be able to still enjoy things as a human would.
- The design of his face is based on his previous appearance as a human at the same age (19 years old currently).
- He has a built-in sleep mode.
- Cleaning his body requires a high-pressure shower, like a car wash.
- The sphere-shaped arm components are for everyday use.
- ONE stated a fight between him and Sonic would end in a draw.
- When not in battle, Genos can change into special arms dedicated for house chores:
- His right hand comes with a built-in vegetable peeler.
- The palms also contain ports that allow him to blast out warm air to dry dishes.
- In an official illustration, a drink bottle opener is built into his right shoulder.
- In the manga's Q&A special, it was commented that Genos (when equipped with 'housework arms') can become a top-class housekeeper.
- In order to become stronger, Genos carries with him extremely detailed "training diaries." A common running gag is that he will immediately scribble down any "words of wisdom" and "training techniques" from Saitama. However, much of the information seems "irrelevant" such as detailed drawings of how to "properly hold and read a manga while slouching on a futon," how to hang laundry on the washing line, and nutritional reports of Saitama's food. Only King seems to realize how useless this so-called "wisdom" is.
- Genos cuts off his sleeves because his shoulders can't fit in them. He also thinks that they are ugly. Furthermore, he thinks that it is troublesome when he is using the weapons in his arms.
- Genos got his piercings after he became a cyborg.
- Genos is too heavy to swim under normal circumstances.
- During a stream, Murata drew a Genos-Cinderella alternative universe, featuring Genos as "Deshiderella" (弟子デレラ, Deshi derera) and Saitama as the Prince, with the quote “I’m a Prince for a hobby!” The other characters were, King as The King, Tatsumaki as The Stepmother, Sonic and Fubuki as The Stepsisters, and Dr. Kuseno as The Fairy God Mother.
- In Murata's stream when describing what ethnicity the characters would be in the real world Murata stated Genos looks German.
- In the 2017 One Punch Man Halloween cover, Genos was depicted twice:
- The first depiction shows a bunny Genos with golden arms holding the tube of a rabbit-shaped vacuum cleaner in one hand and a pink duster in the other. In this form he wears a bowtie, a pair of black bunny ears, a white scut and trouser braces.
- The second depiction shows a devilish Genos with purple wings, a pair of horns and a black armor. Genos is also holding a demonic carpet beater and a frying pan.
- The kanji that Genos' name is written in (鏖) mean "genocide". However, the same kanji also carries a second meaning: "to fight fiercely until the end." The Chinese pronunciation of that kanji is 'ao', which is a homophone for the Japanese word for blue. Blue is a recurrent motif associated with Genos: it is the color his core glows as well as a component of one of his attack forms. Outside the manga, the title of his character song is 'Burning Blue', his core and cogwheel motifs are in blue, as are the flowers he's portrayed with in some merchandise (baby blue eyes, Nemophilia menzeisii, to be precise).
- Murata wanted to call the move Genos did inside Elder Centipede "Super Spiral Incineration Cannon", but ONE suggested on simply using "Super Incineration Cannon".
- Murata noted that Promoted Rook's design was based on ONE's illustration of Genos's dreaming of his new designs. Dragon King is also a pun to Genos's fighting image of a dragon when he used Thunder Drill Cannon.
- Genos' eye (in the anime) has PSO-1 Russian reticle (Прицел Снайперский Оптический, Pritsel Snaipersky Optichesky, "Optical Sniper Sight"), commonly used in the Dragunov rifle.