I'll be super disappointed if the MC doesn't bang at least 5 of the characters introduced so far. Which obv. includes Ryuji.
I also have a hunch it's going to be something along the lines of feelings, relationships, bonds as the main theme / interest for our MC. The series started out with him hanging out with his friends, as well as being captivated by a "blue" Shibuya. More than that, since he is such an honest-to-god fella most of the time, he keeps building important connections with people, shaping both his personality as well as his talents.
Kinda sad how he keeps missing out on meeting Mori-senpai, they already dug each other in HS, and having that sort of relationship would definitely bump his art for various reasons. I'm sure we'll get into relationship drama later on in the story, but overall this is really interesting so far!