I'm So in Love With You(2020)

Suki de Suki de, Daisuki de

Iori's your average high school student... except that he couldn't be without Hazu ever since he was born. Hazu's 5 years older and friends with Iori's older brother, and is busy working as a celebrity and model. He's gorgeous and mature, but has a little bit of a mischievous side to him... He's been turning down Iori all of these years, but the two are overjoyed just being around each other! Finally on the day Iori graduates from high school, something seems different...?

(Source: MangaPlaza)