Sakura, Saku.

When Saku Fujigaya suffers an accident on a train, a mysterious boy steps in to rescue her before vanishing without giving her the chance to express her gratitude. Deeply moved by his selfless intervention, Saku makes a personal vow to never ignore strangers in need, dedicating herself to helping others just as he helped her. Her only connection to her unknown savior is a single note left behind, bearing the name "Ryosuke Sakura." Determined to find him and deliver her thanks, Saku eventually uncovers a promising lead at her high school. She learns that a fellow student named Haruki Sakura has an older brother who matches the name Ryosuke. Seeing an opportunity to finally reach out to the boy who changed her outlook on life, Saku approaches Haruki with a heartfelt thank-you letter, asking him to pass it along to his brother. However, instead of agreeing to this simple request, Haruki unexpectedly refuses. His puzzling rejection leaves Saku confused, sparking a new mystery surrounding the Sakura brothers and the true events of that fateful day on the train.