Watch TOUGEN ANKI

Hayate brings Yaoroshi to meet the other members of the Oni Brigade. Having raided Momotaro bases across the country, the group now sets its sights on a laboratory built where Kegon Falls once stood. Though fewer than ten strong, they are undaunted by the hundreds of enemies they expect to face. Meanwhile, Shiki and the others reach a seemingly deserted colony near the falls while searching for Yaoroshi. Keeping their guard up, they encounter a badly wounded man named Enomoto. An Oni himself, he explains that the colony was home to Oni living quietly apart from humans to avoid harming them if they lost control. But the Momotaro attacked, taking everyone else, including his daughter, Remi, to the laboratory as "materials." As Enomoto weeps in despair, Shiki promises to bring Remi back.

The Oni Brigade operates independently, fighting the Momotaro without answering to any organization. Its general, Hayate Todoroki, arrives at Rasetsu Academy to recruit Shiki, a Child of Kishin. Shiki rejects Todoroki's invitation to join his campaign to wipe out the Momotaro, but Yaoroshi sympathizes with his cause and leaves with him. When Shiki tries to go after Yaoroshi, the others believe they should respect his decision. However, Shiki realizes that the Oni Brigade also targets noncombatants and Momotaro living ordinary civilian lives. Momotaro or not, killing those who mean no harm is wrong, and Shiki doubts Yaoroshi understands what he has signed up for. Determined to stop his friend from heading down the wrong path, Shiki convinces Mudano, Kougasaki, and the others to pursue him together. The Oni Brigade's next destination is Kegon Falls, where a secret experiment is underway...

Homare and Shiki reach the summit, followed by Juji, Kuina, and Rokuro. Only Jin and Yaoroshi remain. As Yaoroshi lashes out at those around him, Jin points out that his impatience is causing trouble for his teammates. Just then, Nekosaki and Innami appear. Cornered by two powerful opponents, the pair have no opening to escape. Suddenly, however, the giant hand Innami has created is blasted away. Guided by Juji's ability to locate enemies, Shiki is providing sniper fire from the summit. With Shiki keeping Nekosaki and Innami at bay, Jin drags the wounded Yaoroshi up the mountain, finally reaching the top. Mudano reveals that the training was meant to help the students find comrades to fight alongside and nurture their hearts. But Yaoroshi angrily rejects the lesson, declaring that Shiki and the others are not his comrades.

Yaoroshi joins the Oni Brigade. Shiki pursues him to Nikko, where a sinister research facility awaits.

The students must climb a mountain within 24 hours during a blizzard, dodging two rival professors.