Dekoboko Sugar Days (manga)

Yuujirou Matsukaze has been close friends with Rui Hanamine since the two of them were children, and at that time, Yuujirou was the one who stood up for and took care of his adorable, soft-hearted friend. But as it turns out, Yuujirou's childhood dreams end up growing a little too big to handle -- or, rather, too tall! At over six feet in height, the cheerful and happy-go-lucky Rui towers over his would-be protector... and still has no idea Yuujirou's had a crush on him since they were kids!