Orange

In Matsumoto, Naho Takamiya, a second-year high school student, receives letters sent from herself ten years into the future. Her future self asks her to prevent her "biggest regrets", which has something to do with the new transfer student from Tokyo, a boy named Kakeru Naruse. At first skeptical, Naho begins to believe the letters as they accurately predict events. When the letter asks her not to invite Kakeru to go out for the first day, Naho and her friends (Hiroto Suwa, Takako Chino, Saku Hagita and Azusa Murasaka) decide to invite him anyway. Kakeru ends up not attending school for the next two weeks.

Wanting to prevent another mistake, Naho resolves to do what the letters order her to do, such as volunteering on a softball round, encouraging Kakeru to join the soccer team, objecting to him pursuing a relationship with an upperclassman, and insisting they watch the fireworks alone. Naho learns from the letters in the future Kakeru is dead, having committed suicide one day after Valentine's Day in the same school year in which he enrolled.

[https://en.wikipedia.org/wiki/Orange_(manga)]