Kazuya Miike, a melancholic yet attractive high schooler, composes his inaugural love letter. The addressee is a fellow female student he catches a glimpse of during his daily commute, known as "Hifumi-san". However, due to a misreading of the name, the letter winds up in the possession of the recipient's elder brother, Hifumi Utakane. How will this accidental communication shape their budding connection?