The summary is incorrect. Heeju nuna is Yuri's cousin. Not sister. Also, it hasn't said that Mr. Lee isn't allowed to supervise students because he's too depressed, so I am not too sure why the translator said that.
I hate that the characters are being described as "the uke of our story" as if their sex position is their most defining feature. And at this point, we haven't even had any sex scenes anyway, so it seems presumptuous to use. Also, the translator shouldn't be mentioning Mangago. It's an illegal website, so you really shouldn't be advertising it.