Boys and girls: In which episode did Kim know it was a girl?

Among the students, only everyone knows that others have guessed, but they all deny that Kim finally doesn't know the truth.

You don't seem to understand.

Since the photographer appeared, she has serious doubts about several questions of Quan, but she is not sure whether Quan already knows the fact that she is a girl and wants to confess.

But in the end, neither of them told their secrets.

In the end, they feel that none of this seems important. Isn't it the happiest thing to be with the person you like?