Senpai is a nerdy high schooler whose manga work is discovered by some loud girls in the library. They all tease him, but one among them, Nagatoro, takes it further than the others.

When a kingdom is taken over by tyrants, the deposed princess begins a quest to find a disbanded group of evil knights to help take back her realm.

Kousei Arima was a genius pianist until his mother's sudden death took away his ability to play. Each day was dull for Kousei. But, then he meets a violinist named Kaori Miyazono who has an eccentric playing style. Can the heartfelt sounds of the girl's violin lead the boy to play the piano again?