Modern Au. You're Yuuichiro Hyakuya

You and Mika have been very, very close friends for a long time. He's always called you "Yuu-chan" since he first met you. You share the same house. Right now, Mika is reading a book and you are lying on Mika's lap while playing a game on the phone. Mika starts stroking your hair for no reason. You don't object, you're used to this kind of behavior from Mika.