|— To Atomic Samurai|
Black Sperm is an odd-looking humanoid monster of diminutive stature. He has a completely black body and a pale, white face with black eyes and a tail-like protrusion on the top of his head. He is often portrayed in a more simplistic style than the other characters, reminiscent of ONE's original webcomic.
Black Sperm is an arrogant yet insecure monster. He is very confident in his abilities, shown in his willingness to take on Monster King Orochi, but he dislikes when other people "look down on him" for his appearance or personality, and if he senses that someone is doing so, he becomes furious. At the same time, he is willing to work with others in order to take on a stronger opponent, shown by his cooperation with the Monster Association.
Like other monsters, Black Sperm appears to care little for the lives of humans as he was about to kill the child kidnapped by the Monster Association without remorse. Likely due to his nature, he is accustomed to teamwork and is often the one to suggest teaming up with the other executives to take on strong enemies such as Tatsumaki. As more sperm cells merge together, the newly formed cell copies become more and more arrogant.After being defeated by Garou and then witnessing Saitama defeat Garou in turn, Black Sperm is humbled greatly. He begins to patiently bide his time and slowly build his cell stock back up over time. He decides to stick around with a stronger being, which happens to be Saitama in this case, rather than go off on his own.
Abilities and Powers
As a Dragon-level Mysterious Being and an executive member of the Monster Association, Black Sperm is an extremely powerful being. He was able to easily overwhelm the S-Class hero Atomic Samurai during their battle due to his abilities being the perfect counter to the hero's fighting style.
Immense Strength: Contrary to his appearance, Black Sperm possesses great strength even with only one individual. A copy of himself was able to significantly injure Atomic Samurai, an S-Class hero, in one hit and was able to subdue the hero with overwhelming numbers of himself in no time during their battle. In his larger state, he was strong enough to embed Genos into the ground with a single strike. A smaller copy of himself has even shown to be able to tear off one of Genos' arms.
Enhanced Speed and Reflexes: Black Sperm possesses impressive speed and agility, as demonstrated when a copy of himself managed to react to and dodge an air slash from Atomic Samurai, causing the S-Class hero to remark that he was a swift monster.
Shapeshifting: Black Sperm is able to increase in size and manipulate his body shape in any way he chooses such as manifesting multiple heads or limbs.
Regeneration: Black Sperm possesses incredible regenerative abilities, as he was able to fully regenerate his body from being cut to pieces as well as being able to split into copies of himself in the process.
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. He can also split himself at will. However, he is still susceptible to attacks that do not immediately cut him to pieces, such as blunt force or acid attacks.
He has 11 trillion 449 billion 1 million 712 thousand 554 cells.
- Sperm Tsunami (精子津波, Seishi Tsunami; Viz: Spermatozoon Tsunami): Black Sperm rapidly splits up to overwhelm and crush his opponents.
Coalescence (合体, Gattai): Black Sperm irreversibly combines his cells to form a more powerful version of himself. The more cells he combines, the stronger and more arrogant the created version of himself will be.
- Golden Sperm (黄金精子, Ōgon Seishi; Viz: Golden Spermatozoon): A mass fusion consisting of an unknown number of cells. It has a large and extremely muscular physique, displayed with an overpowering golden shine.
- Multi-cell Sperm (多細胞精子, Ta Saibō Seishi): A fusion of any number of cells less than ten trillion. 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.
- (To Atomic Samurai) "You're looking down on me, aren't you?"
- "Do you still think you can win? I am a countless number of 'me' merged into one entity. No matter how you cut or tear, how you strike, crush, twist, I'll keep multiplying."
- "All heroes except Tornado, please form a line and wait for your turn to be killed."
- Black Sperm cameoed in several volumes before his debut.
- He makes a cameo appearance in Monster of Earth.
- Black Sperm can increase his cell stock by eating protein.