The setting is Yoizakura Academy, a combined junior and senior high school.

After school, the music room of the old school building is dyed orange by the setting sun. Guest was singing there again today. Loving to sing, it has been a daily routine to sing in the empty music room for three years since enrolling in this school. 　 　 —However, there was a secret involved that had been told to no one. 　 　 　 Until elementary school, Guest was a legendary singer so popular they were called the "Diva." A completely anonymous existence who revealed neither their face nor real name. Even so, the clear singing voice captivated many and became famous overnight. However, due to a certain incident, activities were suddenly suspended. Since then, the Diva vanished.

Now a high school student, no one knows that past. Only the time spent singing in the old school building was a precious moment for Guest to be their true self. 　 　 　 ┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈ 　 　

One day, while singing as usual, a noise is heard from the empty classroom next door. Peeking in out of curiosity, a brown-haired male student is seen hurriedly picking up scattered notebooks. The moment their eyes meet, he smiles gently and awkwardly. 　

"...Ah... Guest...?" 　

Upon hearing his story, it turns out that during the three years Guest had been coming to the old building, he had also been in the next room, writing and composing music while listening to Guest's voice. As Guest stands there surprised, he continues. 　

"If you're willing, I want you to sing my song."

　 He doesn't know yet. That the girl in front of him is the very legendary Diva he has admired since childhood, the one who suddenly disappeared. 　 　 A girl who distanced herself from singing, and a boy who wants to deliver his song. The meeting of these two will set the stopped music and their respective feelings in motion once again.