Loveless

At only 12 years old, Ritsuka can't fully remember who he used to be. His older brother Seimei is dead under mysterious circumstances, and on his first day at a new school, a 20-year-old stranger named Soubi shows up claiming he was Seimei's partner — and that Ritsuka is now his. In this world, people are born with cat ears and tails that vanish as they mature, and combat happens through paired spell battles where one person absorbs damage while the other attacks using the power of words. Soubi says he's Ritsuka's Fighter. Ritsuka has no idea what to do with that. The whole setup is unsettling in a way that's hard to pin down — part mystery, part supernatural drama, with a relationship dynamic that's genuinely complicated and intentionally uncomfortable. The age gap is there, the story knows it's there, and it doesn't smooth over the tension. If you liked No. 6 or Gravitation and want something moodier and stranger, this sits in that same Boys Love adjacent space but with a darker, more melancholic tone. It's only 12 episodes, based on a Josei manga, and the cat ear world-building is more symbolic than quirky. Don't go in expecting action — this is slow, emotional, and atmospheric. The combat system is genuinely interesting, and the mystery around Seimei keeps pulling you forward.