Yaoroshi walking out to join the Oni Brigade is the gut punch here, not some random villain but a kid from Rasetsu Academy choosing the Momotaro eradication over everyone he trained with. Shiki doesn't chase him for honor or rivalry, he goes because he knows Yaoroshi's new crew doesn't care who's noncombatant and who isn't, and that distinction is the whole moral spine of this arc. Stacking that against a black-site research facility perched on Kegon Falls gives you two separate horrors running in parallel, one personal and one institutional, and Tougen Anki has never been shy about letting those collide badly. After Kyoto and Nerima already raised the stakes, this is the arc where the show asks what these students actually became stronger for. If you've been riding with Shiki since the academy days, watching him run toward a friend everyone else has already written off is exactly the gut-check you signed up for.

The Nikko Kegon Falls Arc is the sequel to Tougen Anki, a supernatural action series with a thread of mystery. Its world rests on two bloodlines, Oni and Momotarou, handed down through certain humans for generations. Long ago the Oni kept to themselves until an invasion led by Momotarou broke their peace. Over thousands of years the two sides grew into the Oni Agency and the Momotarou Agency, and they have fought ever since. The first season introduced Shiki Ichinose, who discovers his Oni ancestry after a sudden Momotarou attack. This new chapter takes its name from Kegon Falls in Nikko.