One thing I kinda like about this manga is the romance, because it's there, and yet none of it revolves around the main character. I think that's why it's not labeled as romance, because there are no love interests for Shintarou.
It's kind of facinating, and oddly refreshing. It's like I'm reading a story where the main character is really a side character in someone else's story. I wish more Mangakas would try to write more stuff like that.
"Here's an interesting and complex guy/girl character! There's romance, but nothing involving them as anything more than stepping stones or tangential characters so we can use them to examine more complex and relatively untouched themes!"
I dig it.