No clue if it's the one you are pointing at (3th row, 3th image) but you'll unlock that by not being too rational about your conversation with the Principal!
It is exactly that one. Now I know why I didn't get it. (I try to be rational at all times [or at least I try to]).
This is the first story from Itch that has me on the lookout for more content in a while. So please do keep this up!
Btw, Dian using his sword like a sledgehammer against Moonie makes me wanna bonk him with a baseball bat.