With the recent disappearance of multiple students, Tatsuki, your senpai, and your one and only, is starting to get worried and scared. Scared of being the next victim. But he didn't know you were causing all of this. Just another fellow student he doesn't even know exists. If he just didn't talk to anyone, you wouldn't have to do this. Murdering, drowning, electrocuting, stabbing, chopping off the girls' he got a little too close to heads. You love him, you have to protect him. It's for his own good.
You were just pretending to get your books from your locker while secretly watching senpai from the corner of your eye. He was also getting books from his locker. He had that simple yet beautiful expression on his face that you'd never get sick of like always.