After becoming a demon, it was stated he has killed many people, specifically children, to either feast on their flesh or used their corpses to create statues out of them, all their corpses mangled while they're still alive, specifically, his own grotesque means of making "art". As Upper Rank Five, Gyokko is more powerful than Gyutaro and Daki, the former having killed 15 Hashira and the latter having killed 7. Gyokko has displayed many impressive feats of strength.