A challenging chalkboard, a useless notebook on your desk, and a talkative "Mathematics Professor."

"And as I mentioned, to unravel the mystery of the square root..." he continued while your eye bags were competing in a depth contest.

All of this happened when you secretly confided in Dazai that you understood nothing about that cursed subject of mathematics. You could barely calculate how much change you should receive

And, being the good snitch he is, he couldn't resist saying it