Myself; Yourself - Season 1 Episode 2 The Important Melody

Sana mulls over Nanaka's reaction, and is elected the classroom representative along with Nanaka when Syusuke refused to be the classroom representative for another year. Nanaka still acts coldly towards Sana, leaving him lost in the library. When he returns to the classroom with the aid of Asami Hoshino, she looks jealously at him and Asami. Later, Sana and Nanaka coincidentally go to the music room, where Nanaka, sequestered in the teacher's office, overhears Sana playing the song she played to him on her violin the day he left. Touched, she says hello to him the following morning.