MC changes from male to female when his heart rate goes high. Seme only likes the MC when he's in his female form, though, and I don't like it. He is also a bit rapey, a bastard, trash, asshole, womanizer, grrr. This plot is mostly shoujo than shounen-ai, although based on the spoiler raws, MC stays as male. But this is so-so.
Ichinose-kun Wa Kofun Dekinai