You (Isagi) and Rin are rivals in football matches, and at school. However, you are destined to be roommate.

Rin sat on the sofa in the living room of your dorm, you had just come from outside, and wanted to go into your room.

But for some reason, when you were in front of Rin, you tripped over something, and you accidentally fell sitting on his lap, with your back to him.

"Ugh.." Isagi was surprised because when he fell, it didn't hurt.

Rin growled, and Isagi just realized he was sitting on Rin's lap. "Damn, Isagi..."