He started out as a Demi-Hollow chained up in a hospital—basically stuck in limbo. Don Kanonji, trying to be a hero, accidentally freed him by removing his Chain of Fate, which fully transformed him into a Hollow. His appearance is pretty frog-like, which fans often note gives him a weird, squat look compared to other Hollows.
His whole fighting style revolves around this acidic slime he can spit. The stuff bonds to whatever it hits and then hardens, turning it solid. He used this to lock down Ichigo's sword—sticking it to both his own hands and the hospital roof's guard rail to pin Ichigo in place. It was a solid strategy while it lasted.
Ichigo cleaned up Don Kanonji's mess by taking him down and killing the Hollow before things got worse.
Content compiled by AnimeList.moe from publicly available sources.
