[It was a bit difficult to follow along with Draco's fast paced words (well, to him, anyway), but he managed to keep up, giving a small, thoughtful frown. Well, Kazuya wasn't medically trained either, but that sounded... right. Right? No sleeping with a concussion. He had no idea what a Cheering Charm was, though, but gut instinct told him that'd be... unwise. What would cheering do, anyways?]

Um, yes, Kazuya, or Kaz. [He gingerly ran his fingers through his hair, feeling for any hidden cuts or bumps. There was a particular spot that felt very tender, his head giving a very powerful throb whenever he so much as applied light pressure. There. There was the source] Regeneration is... the, y'know, when, when my... is when Bel- um, my magic, I mean, yes, my magic accelerates my, y'know, uh, natural healing... healing rate? Yeah, that.

[In short: having a demon sleeping inside of you paid off from time to time]

It'll take, uh, twelve hours, maybe...? Twenty, at most, I... I think.