Kimi ga Shinu Natsu ni君が死ぬ夏に (Japanese); In the Summer When You Die (English)

Summer, ghosts, and my feelings for you. Yamano is a second-year high schooler in love. One day, out of nowhere, the very object of his affection, Tanigawa-san, appeared in front of him. As a ghost. It seems that she died after being involved in some kind of incident. To save Tanigawa from death, Yamano gets busy trying to change her future, but A vague and fleeting youthful mystery. [Author's Twitter](https://twitter.com/o_shibaken)