You're looking down on me, aren't you?.
— Black Sperm

Black Sperm (黒い精子, Kuroi Seishi) is a Dragon-level Mysterious Being and an executive member of Monster Association, and one of the few Dragons in the organization who first appeared during the S-Class Heroes' attack on the Monster Association. As Golden Sperm he's considered to be the most powerful member of the Monster Association right after the Monster King Orochi himself.

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

After the Monster Associations downfall, he became Saitama's pet alongside Overgrown Rover and is currently entrusted with Forte, Chain'n'toad and Butterfly DX.


Black Sperm is a humanoid monster with a fully black body and a white face, with an antenna on top of his head.


Black Sperm seems to be very confident in his abilities shown in his willingness to take on Orochi and dislikes when other people "look down on him since he is a sperm looking creature".

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

He appears to care little for the lives of humans as he was about to kill the child kidnapped by the Monster Association without remorse. As more sperm cells merge together, the newly formed cell copies become more and more arrogant. When Golden Sperm is formed, the newly formed sperm copy becomes extremely arrogant, not even caring about his other sperm copies and telling them to simply merge with him due to his superior power.


Human Monster SagaEdit

Monster Association ArcEdit

He is present at Gyoro Gyoro's speech at the Monster Association HQ and questions serving under Orochi, stating that they are only allies at the moment and are only there to crush the Hero Association.[1] He reluctantly backs off upon Gyoro Gyoro's speech about challenging Orochi for leader to himself.

After Gyoro Gyoro tries to promote Garou as one of their executives, Black Sperm shows surprise from this action and sarcastically quips to Gyoro Gyoro for giving Garou such a lucrative offer.[2]

Black Sperm, and several other monsters, is called upon by Gyoro Gyoro for a meeting.[3]

Black Sperm is seen feeling the shaking from Saitama's punch on Overgrown Rover.[4]

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

Black Sperm appears when Busaiku is separated from Garou. Black Sperm chases after the kid in hopes of killing the child. Atomic Samurai steps in and manages to allow the kid to run to safety. However, Black Sperm soon overwhelms Atomic Samurai due to his ability to split into numerous versions of himself, as well as regenerate at will.

After Tatsumaki destroyed the Monster Association HQ, Black Sperm and several other Dragon level monsters emerged from the rubble to attack her. When Psykos temporarily cuts off Tatsumaki's psychic power, Black Sperm grabs Tatsumaki in a giant arm and attempts to crush her. The esper was saved by Genos, but the cyborg immediately had his arms ripped off by Black Sperm and Gums. Black Sperm and the rest of the monsters then proceed to watch Psykos play around with Tatsumaki until Genos decided to attack Fuhrer Ugly. Before Fuhrer Ugly could retaliate, Bang suddenly joins the fight and effortlessly kills two of the Monster Association's remaining members before being knocked out by Homeless Emperor. Black Sperm then takes this opportunity to knock Bomb unconscious.

Black Sperm then decides to continuously beat up Genos until King finally decided to take a stand. The remaining members of the Monster Association then try to think of a way to take on King. After King managed to buy some time against the remaining monsters, Tatsumaki began to recover and turn the tide of the battle. In an attempt to defeat her, Black Sperm fused one trillion copies of himself into the much stronger Multi-Cell Sperm. Unfortunately for Black Sperm, the newly formed sperm is effortlessly killed by Tatsumaki. Afterwards, Black Sperm sends a thousand copies of himself to perform a kamikaze attack against Tatsumaki to buy time as he takes Busaiku hostage, thus forcing the heroes to simply stand and watch as he fuses ten trillion of himself into his ultimate form, Golden Sperm. This new form proves incredibly dangerous, as Golden Sperm is able to take down Tatsumaki so fast that nobody else could even follow his movement with their eyes. However, this victory proves short-lived, as the newly mutated Garou shows up, destroying 99 of the 100 remaining copies of Black Sperm and killing Golden Sperm after a brief battle that none of the heroes could even see. Now down to only one life, Black Sperm slips away to watch the battle from afar. 

Psychic Sisters Arc Edit

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

The next day, after encountering Saitama, Black Sperm and Overgrown Rover follow him home as pets. The two formerly dangerous monsters are currently entrusted to Butterfly DX and Chain'n'toad due to Forte losing a bet with Saitama all of a sudden, when he finally witnesses how strong Saitama is.

Abilities and PowersEdit

As a high-ranked member and a Dragon-level Mysterious Being of the Monster Association, Black Sperm is an extremely powerful being.

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

Sweet Mask himself says that even if all of the S-Class heroes fought Golden Sperm, it would still be a very difficult task to defeat him. Along with this, he was the only one besides Saitama who was able to fight against evolved Garou on equal footing, even if it was only for a few moments. It is a fair assumption to say in the webcomic, Golden Sperm is the most powerful member of the Monster Association. Murata does not know who is stronger between Golden Sperm and Orochi in terms of raw strength.[5]

Physical AbilitiesEdit

The following section contains Webcomic spoilers. You have been warned, manga-only readers.

Immense Speed and Reflexes: Black Sperm is able to dodge Atomic Samurai's slashes. As an individual Black Sperm, he was able to keep up with Genos's immense speed effortlessly.

Immense Strength: Contrary to his appearance, Black Sperm has great strength and was able to badly damage Atomic Samurai in one hit. He was also capable of lifting a huge boulder with ease.

Immense Durability: As a Dragon-level monster, Black Sperm possesses enormous durability. As an individual Black Sperm, he was able to easily withstand all of Genos and Atomic Samurai attacks.

Shapeshifting: Black Sperm is able to increase in size and manipulate his body shape in any way he chooses.

Replication: Instead of being killed, whenever he is dealt a fatal blow that would typically result in death, Black Sperm will split into even more copies of himself if he still has enough cell stock. However, this ability does have a weakness: if the sperm copies decide to merge into one being, that merged sperm form will not regenerate if it is killed.

Fighting StyleEdit

Hand-to-Hand Combatant: Black Sperm mainly relies on his brute strength and his skill in close-quarters combat during battles.

Coalescence (合体, Gattai): Black Sperm permanently combines his cells to form a more powerful version of himself. The more cells that he combines, the stronger and more arrogant the created version of himself will be.
Multi-Cell Sperm Webcomic
  • Multi-cell Sperm (多細胞精子, Ta Saibō Seishi): A fusion of any number less than ten trillion cells that combine. The strength of this form has yet to be observed as the only Multi-cell Sperm observed was quickly taken out by Tatsumaki.
Augmented Strength: His strength was presumably augmented, but it was not shown due to Tatsumaki eliminating it instantly.
Augmented Speed and Reflexes: His speed and reflexes were presumably augmented, but they weren't shown due to Tatsumaki eliminating it instantly.
Augmented Durability: His durability was presumably augmented, but it still wasn't enough, as Tatsumaki was able to nearly effortlessly eliminate it.
  • Golden Sperm (黄金精子, Ōgon Seishi): This state requires at least ten trillion cells to create. This form vastly increases his powers to amazing heights and he is able to defeat an injured Tatsumaki, as well as temporarily fight with evolved Garou, something none of the other S-class heroes could do. Sweet Mask went so far as to comment Golden Sperm was beyond his abilities, and that even if all the S-class heroes ganged up on him, it would be a very difficult fight.

Golden Sperm trades blows with Monster Garou

Augmented Strength: As Golden Sperm, he was powerful enough to partially penetrate through Tatsumaki's barrier as well as cause great destruction and destroy nearby rocks in his battle with Garou.
Augmented Speed and Reflexes: Golden Sperm is so fast that he was easily able to blitz Tatsumaki in a split second with no visible effort. He is also so fast that he was able to keep up with Garou's speed, with none of the conscious S-class heroes being able to see their fight.
Augmented Durability: Golden Sperm has incredible durability, as he remained unfazed when Tatsumaki attempted to break his neck, and was also able take several attacks from evolved Garou and continue fighting.
Psychic Resistance: Golden Sperm is able to very effectively resist an injured Tatsumaki's psychic attacks with very little effort. However it has been confirmed that if she were at full power, he could lose.[6]
Golden Sperm Webcomic

Golden Sperm Full Appearance

Kamikaze Attack (,): Black Sperm sacrifices a number of his cells to attack a target. This has been mainly used as a distraction.

Major BattlesEdit

Webcomic notice The following section contains Webcomic spoilers. You have been warned, manga-only readers.
Participants Chapter(s) Episode(s) Result
Atomic Samurai vs. Black Sperm 62,63, 67, 68 None Win
Tatsumaki vs. Fuhrer Ugly, Gums, Evil Natural Water, Homeless Emperor, Black Sperm, Psykos 71, 72, 73 None Win
Genos vs. Fuhrer Ugly, Gums, Evil Natural Water, Homeless Emperor, Black Sperm, Psykos 71, 72, 73 None Win
Bang vs. Fuhrer Ugly, Gums, Homeless Emperor, Black Sperm, Psykos 72 None Win
King vs. Evil Natural Water, Homeless Emperor, Black Sperm, Psykos 73, 74 None Interrupted by Fubuki and Zombieman
Sweet Mask vs. Black Sperm and Evil Natural Water 75, 78 None Interrupted by Tatsumaki
Tatsumaki vs. Black Sperm 79, 80 None Black Sperm holds Busaiku hostage and Golden Sperm forms
Garou vs. Golden Sperm 81, 82 None Loss


Webcomic notice The following section contains Webcomic spoilers. You have been warned, manga-only readers.
  • "You're looking down on me, aren't you?"
  • "All heroes except Tornado, please form a line and wait for your turn to be killed."


  • ONE stated that Tatsumaki in her best shape could have beaten Golden Sperm.[6]
  • ONE stated that Golden Sperm is equal in strength to Ossan (the main protagonist of Makai no Ossan, another of ONE's works).[6]
  • Murata is uncertain who is stronger between Orochi and Golden Sperm, but states that Orochi has superior techniques.[7]
  • Black Sperm can increase his sperm stock through eating protein.
  • Black Sperm has cameoed in several volumes before his debut.


  1. One-Punch Man Manga; Chapter 79, page 31
  2. One-Punch Man Manga; Chapter 86, page 25
  3. One-Punch Man Manga; Chapter 94, page 150-151
  4. One-Punch Man Manga; Chapter 106, page 26
  5. One-Punch Man Stream; 5/19/2018
  6. 6.0 6.1 6.2 One-Punch Man Interview; Niconico Interview
  7. One-Punch Man Stream; 5/19/2018