Onmyou Taisenki - Season 1 Episode 25 Open.Zero Drive

Riku has regained his memories and is reunited with Kogenta. He also meets Yakumo again, who tells him about the Fukumaden and the past. There once was a man named Utsuho, and he had the terrible power to control the Youkai. He used the Youkai to attack Kyoto, the capital city at the time. The Toujinshi used their power to fight Utsuho and eventually won. Utsuho and the Youkai were sealed in a dimension far away. The Toujinshi split into two factions: the Ten-ryuu to guard the seal and the Chi-ryuu to destroy the Youkai that leaked out of the seal. The place where Utsuho is sealed is the Fukumaden. Soon after, the Jin-ryuu Toujinshi Taishin and his Shikigami, Magahoshi, return and attack the group. Riku runs away, and Yakumo chooses to fight him alone. With his new Zero Drive, Yakumo seems to be making short work of Taishin.