I had to read it twice to get what he meant with "can't only think about yakishimaru", me shoujo sense must be getting dull
It's belated but he's starting to put effort into stuff which is a big departure from how he was in the past (listless, disinterested in anything at least to his peers at school). He will prob. join a part-time job i.e. paid gig other than helping out his mom at home/cafe. He is looking to define himself other ways than just "I love 80s culture" and "I love yakishimaru". That smile was the male equivalent of when CGCT pull the can-do girl smile