Gotta say, the protagonist accidentally making his girlfriend think he's a trans woman is one of the funniest premises for a manga like this I've ever seen. Interesting that permanent transformations DO happen.
Also, the sharp tooth guy feels like he has more depth to him than you might expect. I doubt he really cares that much about whats going on between Akizuki and Chihaya. Also, very cute as a girl! Curious how that happened though, did a Shishizaki cousin kiss him while he was asleep?