高中女生夏澄，爱慕单身英俊的老师藤堂直，同校清一却对夏澄一往情深。而当藤堂克制不住自己的感情，与夏澄淡淡的一吻之后，却忽然不知道去往。五年后，夏澄的姐姐朋子将男朋友回家时，夏澄赫然发现，姊姊的未婚夫竟是朝思暮想的初恋情人藤堂。故事就围绕绕绕爬四个人所著的爱开始展开…。

Kasumi is shocked to discover that her older sister's fiance is the man she first fell in love with five years ago in high school. At the time, he was her high school teacher and ultimately quit his job racked with guilt over their relationship. Kasumi was deeply hurt and struggled for a long time to overcome her sadness. Now the two of them must come to terms with their secret past before the ones they care about in the present are hurt.