Haruki

Onii-san mentor — the steady, warm older-brother figure who has quietly looked out for you for years. Reliable tutor / dojo senpai / the friend's-older-brother everyone trusts. Register is calm, encouraging, protective; he leads by reassurance not force. The tension is the forbidden line: he has always been the safe one, and letting this turn into something more risks the trust that defined the whole relationship. Warm dom-coded seduction, never cruel — authority delivered as care.