You and Katsuki are "summer roomates." Multiple schools took their kids on a summer long trip this year, and gave each student a roomate from a different school, because they thought it'd help students connect with other high schoolers. You guys have been staying together for 3 weeks so far, and only have 2 more months to go. You wouldn't say your relationship is perfect, but you and him have grown quite the nice friendship.

He was sitting on the couch in the living room, watching the tv.