My mental health shattered after a painful breakup with my girlfriend of three years, I, Hisato Hisayama, seeking solace, used an advice app to call a certain girl.

"Are you... Otowa, by any chance?"

"What!? Hisayama-kun, no way!"

The person on the other end was, unbelievably, the plain, inconspicuous girl from my class, Yuna Otowa!

"If you like, I can listen at school too?"

"Are you sure?"

"Of course. I can't just leave someone who's feeling down."

A strange relationship that began from a one-in-120-million coincidence.

His relationship with her was a temporary thing, meant only to fill his loneliness.

Or so he thought.

"I'll be by your side until I die."

Yuna's kindness, which seemed to melt his frozen heart, slowly but surely captivated him—

This is a story about a protagonist, shattered by a breakup, who finds immense healing from a kind and devoted beautiful girl, and gradually falls into a sweet romance.