Sakura, Saku, Vol. 1

Saku Fujigaya would like to thank the boy who helped her, but all she has is a note signed "Ryosuke Sakura." She discovers that a boy at her high school, Haruki Sakura, has an older brother named Ryosuke. She asks Haruki to deliver her thank-you letter to Ryosuke, but why does he refuse?

Volume 1 of the Sakura, Saku manga series by Io Sakisaka.