Sakura, Saku.

A girl named Saku Fujigaya is rescued by a boy after falling onto train tracks, but he disappears before she can express her gratitude. Afterward, she makes a point to assist strangers in need, inspired by the boy’s kindness. The only clue she has about him is a note signed "Ryosuke Sakura." She learns that a classmate, Haruki Sakura, has an older brother named Ryosuke and asks Haruki to deliver a thank-you letter. However, Haruki refuses. The story also includes a one-shot titled "Otome no Itari," along with a prologue and epilogue.