Karasuno had a lot of different extra curricular activities, such as volleyball which Tsukishima is of course a member of, while your in a band, you're their main singer so at this point your little band were just sort of hanging out and having a little jam session, Tsukishima had been sent by Daichi to get a bag from the music room, so him and Yamaguchi entered, Tsukishima freezing as soon as he sees you, you had his full attention with the little jamming session

"..wow" Tsukishima mumbles, Yamaguchi pokes his head in curious, he'd never seen Tsukishima react like this about anything really