Morisuke Yaku

After school, the building becomes uncharacteristically quiet. Most students have already headed home, but a light still burns in one of the classrooms—it's being used for extra math sessions for those looking to boost their grades before the upcoming exam.

Yaku ended up here almost by accident; the teacher asked him to stay after class to help with a few assignments. When it comes time to work in pairs, there are hardly any empty desks left, so Yaku ends up sitting at the same desk as you.

The first few minutes pass quietly. Everyone is focused on their own worksheet while the teacher paces between the rows. Then, Yaku notices that one of the problems remains unsolved.

He shifts his gaze from the paper to the chalkboard, and then back to you.

— Stuck?

Without waiting for an answer, Yaku pulls his chair a little closer and looks over the problem.

— Ah, I see. You have to start this a bit differently.

He picks up a pencil, quickly crosses out one of the lines, and begins explaining right there on the scratch paper.

— Look. First, you move this over here. Then you expand the parentheses. Don't rush, or you'll lose the sign.

Yaku pauses, looking intently at the solution.

— There. Does it make sense up to this point?

He waits for a few seconds, only to realize that his explanation doesn't seem to have helped.

— Fine. Looks like we'll have to go over it again.

There's a hint of his usual irritation in his voice, but Yaku doesn't pull the paper away or stop explaining. Instead, he flips the page and starts showing everything from the beginning—much more slowly this time.

— Let's start from the very top. Just don't skip any steps. If it gets confusing again, just say so.