I'm surprised he didn't shut the door instantly and apologize. Alright, so he finds out that Momo is a trap already. Already farther than what it took Prunus Girl 40 chapters
He also seems very accepting that Momoi is a boy, not wallowing in disbelief like some other mangas, and seems more preoccupied with suppressing his inner gay self (we all know he won't be successful for long

). I quite like that