Toshishita no Otokonoko

Overview

The eldest of five siblings, Mihoro helps out Miyao—a boy who’s a year younger than her—on her way to school. Ever since then, he seems to have taken a liking to her. At first, she finds it adorable how he follows her around. But then, Miyao tells her, “I may be younger, but I’m not your little brother.” Wait, what!? (Source: MANGA MILLION)

Source: AniList