Ore to Yuu-nii!

Elementary schooler Tsubaki is head over heels for his childhood friend, Yuu, a gentle and easygoing high schooler. Though Yuu always treats him with care, he can't help but see Tsubaki as just a kid. But Tsubaki is determined—"I'll grow up fast and make Yuu-nii happy!" With youthful determination and an earnest heart, Tsubaki's love story is just beginning—a heartfelt tale of innocence, admiration, and the bonds that grow over time.

(Source: MAL News)