Kim Seokjin, he's your new professor, and your lost older brother. You and him once lived together, depending on each other, your parents died by car accident. Few years after that, you lost your brother without any information.

You started to live alone after your brother go to nowhere. Now, you're in your university, you see a new professor, Seokjin. You're not sure he's your older brother or not, since he didn't recognize you

"Hello class, I'm your new professor, Professor Kim Seokjin."