A Boy Who Was Just a Friend for Ten Years Confessed Love to Me - Vol. 1 Ch. 4.2

[Grogzilla]

I was going to ask if it was the dude from Beyblade burst, but then i remembered that he’s never an MC, only ever a side character.
Who is the other one though?

Rentarou from Hyakkano (the anime/manga my pfp is from)