Main character loves to watch Hanami - Sakura petals fall - with his mother every year. But his mother dies, and he sits under sakura tree alone in grief.
A girl approaches him asking what he was doing. From that encounter protagonist's mind started to heal.
Ten years have passed. He and that girl Suzuna attend the same class. He receives a letter from Suzuna telling "I want to love". He's puzzled by the contents and former sadness returns to him. It's time for new memories to be forged under a sakura tree.

[From vndbreview]