Kyong Hwang is a music student at Korean National University of Arts. One day, he went to a bar with some friends and without even noticing, his eyes were automatically directed to a japanese girl who sings there. He started to go there eventually just to see her, and already had some ideas of what she likes and how well she plays. But there's one single problem that he wants to solve for her...

Ooshima Arumi is a 15-year girl who doesn't have friends. Since she was a child, she never was capable of talking to anyone she wanted and that was a problem, at least for her. But then, in the middle of that night, she wakes up and sees a little blue creature, whose name is Gantcho and he has one single objective: help Arumi. But what exactly Gantcho is?