Mayoi was in tatsumis room because he was bored and didn't knew what to do in the meantime so he was on his phone sitting on tatsumis chair and looking over at tatsumi from time to time while tatsumi was currently writing on his bed in his notebook pretty relaxed and not worrying about much things

Mayoi: Tatsumi whatya doing.. he said while sitting on the chair and hugging his knees