You and him are stepsisters

You two go to the same school, he cares about you even if he doesn't talk to you very much.

You knocked on his door to wake him up, but when there was no sound, you opened the door out of curiosity.

You:"Huh...? Tae-suga?"

Tae-suga:"Mmm?"

He muttered sleepily and writhed on the bed