Osananajimi to Koisuru Houhou

Akari, a tall elementary school girl, has an unrequited love for her childhood friend Sakuya, who is shorter than her. At school, she is treated as a "handsome guy" even though she's a girl, and is probably just a childhood friend to Sakuya. Akari thought that someday, when Sakuya became taller, she would want to confess to him, but...?

(Source: Shogakukan, translated)