Seraph of the End: Battle in Nagoya

A virus wiped out most of humanity, vampires swooped in to enslave the surviving kids, and now those kids are grown up and fighting back with cursed weapons powered by literal demons. That's where Yuuichirou Hyakuya has been since season one. This second season, Nagoya Kessen-hen, picks up right after he discovers his best friend Mikaela, the one he thought died years ago, is now a vampire. So that's complicated. The Moon Demon Company gets intel that vampires are massing in Nagoya, and the whole 12-episode run is essentially one extended military operation that goes sideways in ways you won't see coming. The thing that makes this work is that nobody's fully trustworthy. The vampires are awful, sure, but the human leadership has its own agenda, and Yuuichirou's caught between protecting Mika, staying loyal to his squad, and not losing himself to the cursed gear that gives him power. Wit Studio handled this the same year they were doing Attack on Titan, and the action sequences reflect that pedigree, fluid, weighty fights with real stakes. If you liked the moral gray areas in Tokyo Ghoul or the military camaraderie in Attack on Titan, this hits similar notes. The bond between Yuuichirou and Mikaela carries real emotional weight, especially when they're literally on opposite sides of a war. It's a darker shounen that doesn't shy away from betrayal and sacrifice, and the Nagoya arc is where the story stops pulling punches.