"Hey, Kou-chin. Sorry to bug you but, will you help me study?" It was a Saturday. There was still a month of summer vacation to go. Due to complicated family circumstances, Kouta - "Kou-chin" - who lives alone meet Chieri - "Chi-chan" - a classmate of Kouta's at the conbini near his house. This ditzy kurogal was his benefactor for the summer. Kouta helped her study - though he could hardly focus - and as a bonus he was endlessly visually entertained. He knew Chi-chan had a boyfriend so...... well, he didn't torture himself with fantasies, but at the same time Chi-chan had a flirty, cockteasing way.