Caster & Mild summary:

One morning after a drunken blowout, Kei opens his eyes to an unfamiliar ceiling and to a valiantly over-helpful man who he also doesn't know, Asahi.

Asahi says he's a friend of Kei's friend Rio, and he tells Kei straightforwardly that he's been interested in him for a while. Even though he's not Kei's type at all, to Kei's amazement, Asahi seems rather attached to him. Since the person he was living with has thrown him out, and he has nowhere to live, he accepts Asahi's hospitality...