My Troublesome Man (2019)

Blurb:
Even from a young age Hira was an introvert, too nervous to speak up, disappearing into the crowd at his high school. From afar he admires his classmate, Kiyoi, ruling as the king of the class with his handsome looks and his aloof attitude. To him, everyone is equally worthless.
With his low self-esteem, Hira is happy to play his part as Kiyoi’s loyal gopher, but even he’s surprised when he finds Kiyoi’s phone number added to his cellphone. Every glance, every scrap of attention is precious. Could these lonely, suffocating feelings actually be love?

Source: www.anisearch.com/manga/94757