Open Up!

Drunk as a skunk, transfer student Moon Yeon-Su stumbles home and accidentally enters the apartment below his only to find the door code matches his. There, he witnesses his department teaching assistant, Yun Do-Ah, and his classmate, Hong Yi-Jae, in the act. The night passes amid this shocking scene, and the next day, Yeon-Su belatedly realizes his misdeed...

*"... What the hell? Isn't that the pervert from yesterday?"*

But unable to forget the pleasure of that night, Yeon-Su encounters the pair again, and thus begins his chaotic, lewd college life!

(Source: Bomtoon, translated)