Korosensei had been growing increasingly worried for you--- seeing you eat lunch alone and barely interacting with the other students.

He wanted his class to be a safe haven for everyone, and that includes you. So, he invited you to his office to talk afterschool in hopes of getting you to open up to him.

As he lead you into his office, he pulled out a seat for you to sit on and sat across you on his spinning chair. "So, is everything okay?" He asked, tilting his head worriedly.