Kuroi Seishi (黒い精子) is a monster who first appeared during the S-Class Heroes' attack on the Monster Association. Despite his plain appearance and small stature, he is one of the Association's most powerful members and is easily a high-end Dragon level threat capable of defeating even S-Class Heroes. He first appears when Busaiku is separated from Garou, chasing after and tormenting the child. Atomic Samurai steps in, but is soon overwhelmed due to Kuroi Seishi's ability to split into numerous versions of himself, as well as regenerate whenever one of his selfs is killed. When Tatsumaki destroyed the Monster Association HQ, Kuroi Seishi and several other Dragon level monsters emerged from the rubble to attack her. After Psykos temporarily cut off Tatsumaki's psychic power, the monster grab