Dr. Kuseno

Genos, just don't do anything reckless. Dr. Kuseno (クセーノ博士, Kusēno Hakase) is a scientist of justice. He performed surgery on Genos and turned him into a cyborg. Despite never having seen Saitama in action, Kuseno is aware of his strength due to how much Genos has talked about Saitama to him. He is also a member of the Saitama Group.

Appearance
Kuseno is an elderly man. He has elongated ears, a large nose, thin light eyes, grayish pupils and a thin frame. His hair is cut into a bowl shape and protrudes away from his head.

Personality
Dr. Kuseno acts very fatherly towards Genos, often expressing concern for him and providing wisdom, drawing from his own experiences. He often reminds Genos not to be reckless and that they are together in their battle. He somewhat worries about Genos' obsessive desire to destroy The Mad Cyborg that murdered his family and often stresses this to Genos to a degree.

In his youth, he was a very justice-driven man who would do anything to achieve justice for mankind even it meant doing reckless things. As a result, seeing Genos being nearly destroyed by powerful monsters due to his recklessness reminds him a lot of himself.

He is a very selfless man since he willing to sacrifice his sleep and rest in his senior age to work tirelessly to give Genos the best weapons and upgrades to help mankind.

History
Four years ago, Dr. Kuseno passed through Genos' destroyed hometown, pursuing the Mad Cyborg who rampaged through it. He found and rescued the sole survivor of the massacre, a boy who begged him to transform him into a cyborg. Kuseno agreed, and modified him into a cyborg, who took on the name of Genos. He was promised by Genos that he would find the Mad Cyborg and destroy him.

They have since worked closely together and the doctor says that they have endured many hardships together. Like Genos, Dr. Kuseno's family were murdered by the Mad Cyborg in one of the villages it went around destroying.

Paradise Group Arc
Kuseno is seen developing parts for Genos, listening to his talk of admiration for Saitama and wanting to surpass his own powers. After hearing this, Kuseno noted that he developed new parts for Genos and that he might be able to become stronger than Saitama.

Garou Introduction Arc
After defeating G4, Genos brings some of its parts to Kuseno, requesting that the doctor use them to make him stronger. Kuseno is surprised that Genos had gotten the parts. Dr. Kuseno further states that Genos' master has given Genos a very reckless goal and asks whether Genos can bring Saitama the next time Genos comes, expressing his concern for the young cyborg. He also asks him about the current whereabouts of the cyborg that they're seeking. Genos replies nothing but expresses his hatred and would want to destroy it. Seeing this, Dr. Kuseno reminds Genos that he is not alone in his fight and not to be reckless.

Monster Association Arc
When Genos was defeated by Gouketsu, Dr. Kuseno spent a whole night fixing Genos' body. Genos is very grateful for his work and Dr. Kuseno noted that thanks to Genos, many new ideas and improvements came and made simple changes in Genos' body that made him stronger. He then warns Genos to be careful and not to be reckless like he was in the past and decided to get some rest.

When Monster Association is about to prepare for their evil plan on annihilating humanity soon, Dr. Kuseno dons a battle suit to defend himself from any other villains’ attacks and comes out to find Genos, rather than using his drones as he wants to understand the field conditions in which Genos operates a bit better. Once he finally found where Genos is Saitama’s apartment safely, Dr. Kuseno is happy to meet Genos’ master Saitama, as well as their other allies whom Saitama and Genos befriend with, such as Bang, Bomb, King and Fubuki in person. Dr. Kuseno thanks Saitama for taking care of Genos, by gifting him a Supreme Hotpot Deluxe Beef Set. As everyone present is hungry, Dr. Kuseno joins the dinner.

After the dinner, Dr. Kuseno took Genos back to the lab and appears to have worked overnight for a second consecutive night to repair and upgrade Genos. Despite his concerns, he fulfilled Genos's request for more power, building a configuration that maximised power at the expense of nearly everything else. He warns Genos to manage the body's power carefully and not to use its full power for more than ten seconds, as the core might otherwise explode, which would kill Genos.

Neo Heroes Saga
After the Monster Association Raid, Genos is away for an extended period of time. After the Neo Heroes reach out to Genos, Dr Kuseno is seen asking Genos what his decision is as the latter prepares to go back into the field.

Neo Heroes Uprising Arc
Saitama and Genos meet with Kuseno to talk about going after the Mad Cyborg in Bofoi's lair. Kuseno entrusts Genos's safety to Saitama, saying that he has come to regard the former as his grandson. He later performs a physical examination on Saitama for research purposes. Unfortunately, he is suddenly attacked and fatally wounded later in that evening by a group consisting of multiple robots including the high-level ones. After Genos and Saitama destroy all of the robot enemies, the latter intends to bring him to a hospital to treat his wounds. However; Kuseno, knowing that he won't survive, makes his last words to Genos, revealing to him that he has left a final version upgrade for him as a secret weapon in the west basement. He advices the cyborg to run as far away from his enemies as possible after equipping that last armor. Before finally passing away, Kuseno discloses that he has always wanted to give up fighting and live peacefully with Genos, and then apologizes to the cyborg for giving him the power to fight and roping him in to his quest for revenge.

The Sisters Who Have Too Many Things Happening
Dr. Kuseno is visited by Genos and was asked for psychic augmentation, but Dr. Kuseno stated that it wasn't physically possible. He later remarked by how bothered Genos was for not being able to fulfill Saitama's task.

Intelligence
Genius Intellect: Dr. Kuseno possesses a great intellect, having created Genos' cyborg body on his own. He is also responsible for the various repairs and improvements of Genos' cyborg body during the story.

Equipment
Body Recovery Drones:  Dr. Kuseno's drones that are mainly used to recover Genos' body parts and assist Genos when he is unable to move. It is also shown that the drone is equipped with a Gatling gun at the end of its tail.

Combat Armor: Kuseno uses a combat armor with a comparable look to a spacesuit that is armed with a rocket launcher on the right shoulder and a cannon on the left shoulder to defend himself against monsters. Genos said that it had "high power levels" and also thought that Fubuki wouldn't be able to handle it.

Quotes

 * (To Genos) "But Genos... even if you are the cyborg fighting for justice... you better not push yourself too hard."
 * (To Saitama) "So you are... Genos' master. Saitama, I presume. I've always wanted to meet you."

Trivia

 * The "kuse" in Kuseno sounds exactly like "kusee" (くせー) an impolite form of "kusai" (臭い) that means "stinky" while the "no" has no direct translation (most likely the common Japanese name ending 野 meaning "field").
 * In the 2017 One Punch Man Halloween cover, Kuseno was depicted as a kappa, a Japanese mythological creature. The choice could have been in reference to Kuseno's pun explained above, as kappas are said to be smelly.