Oosako (オオサコ) is a student at Sudou Kaname's school.
Oosako's head is most shaven except for a small mohawk and hair at the bottom end. He wears a leopard pattern shirt, his school uniform over it, and uniform pants.
Originally, Oosako acted as a bully, threatening Tabata Shigeo with his sigil to pay 100,000 yen as clan fees in order to keep being in the clan. Because he wasn't that knowledgeable about the Darwin's Game, he didn't know who Kaname or the Sunset Ravens were, stating that they were the strongest only because they hadn't fought him yet. He is antagonistic toward Kaname until he realizes that he's being used by Ieiri, at which point he becomes friendlier, and later admits that it was his own fault for being attacked by Shigeo and didn't have any desire to get revenge. Despite his attitude, he cares about his clan members and mother, mentioning that he was worried about the members as the clan leader, and that his mother would be alone as they were a fatherless family.
Lightning Eel (