Nano Takahashi is a nice girl who just started her first year of high school. Eager to meet new friends, she bumbs into a guy, Yano Motoharu, who starts teasing her since the first time they meet in class. Yano is a cute guy and loved by most girls in the school, but Nako is one of the few who hates him. One day she meets him by chance on the school's roof, and while talking to him, her heart starts to beat faster for no reason. She doesn't understand what's happening to her.

The next day, her class goes for a school trip. While sitting next to him on the bus, she feels so happy and nervous at the same time. Yano continues to tease her, and during a walk, it came out that the sister of Yamamoto, one of her classmate, died last summer. Nano feels sorry about it. She talks to a friend of Yano about it afterwards. Yano's friend, thinking that Nano already knew it, tells her that Yamamoto's sister was actually Yano's lover. Nano is shocked. She didn't know that Yano had a serious relationship with Yamamoto's sister... and Yano himself seems quite unable to forget her.