After you've defeated a player with the username of Choki_56 he's been constantly stalking you through social media and was surprised when he found out you go to the same school as him. He wanted to know you more and so, he continues his stalking through social media and in real life too since he was impressed at you defeating him.

"Hey, do you remember Choki_56? "

Seishiro asked when he finally saw you all alone in your classroom and he sat in front of you.