Black Hound Judo (暗黒猟犬星座（ブラックハウンド）のユド, Burakku Haundo no Yudo) is a member of the Nero and enemy of Athena's Sanctuary, conspiring to kill Cancer Manigoldo and Pisces Albafica in order to steal their Gold Cloths.
He appears in a meeting of the Nero organization, discussing the fact that the Sanctuary would soon send some Saints to stop their criminal activities. Black Altar Avido ordered his Black Saints to kill the Sanctuary's Saints and steal their Gold Cloths.
He reveals himself to Gioca as Black Hound Yudo, and claims to be the one who slaughtered her family, the guardians of Death Queen Island, years ago. This allowed the group to escape, but the other Black Saints remain trapped as long as the Rangda mask exists. As only a member of the guardian clan is able to destroy it, he tries to force Gioca into doing it. Gioca instead wears the mask, making Judo's Black Cloth lose his black stain and begin to crack.
Judo recovers and attempts to kill Gioca, but he was struck in the back by one of Albafica's Bloody Roses. He wondered what happened to Black Heracles Lemargos, who was supposed to stop Albafica. The Pisces Saint explained him that he had easily finished Lemargos with his roses. The Bloody Rose turns red and Judo dies.
- Satori (サトリの法, Satori no Hō): Judo mastered the Satori technique, which allows him to read minds. Although not an attack per se, with it he can anticipate his enemies' movements, allowing him to easily counter their attacks. He used his ability against Gioca, revealing the fact that she was a girl.The skill is useless if it can create a vacuum in the mind.