The Gray Jewel - S1.E6

Azuma's companions have won their second Bubuki battle, but the next opponent is one of Reoko's Four Gods who was in disguise as their friend Horino. Hiiragi and the others are shocked to learn that their trusted friend is actually working for their mortal enemy. Kinoa demands to know why she betrayed them, but Zetsubi easily dodges the question; Hiiragi attacks her in rage, but he's no match for the power of Zetsubi's Bubuki. Azuma's suggestion of figuring out what the opponent's Bubuki's power is momentarily calms Hiiragi, but soon enough...