Taiyo Matsumoto is an amazing illustrator and writer but he seems to do the same story in all the works that I've read: two teenage male characters have a coming of age experience with some fantasy or magical realism elements. Typically, one of the characters is exceptional in some regard (an amazing fighter, a great Ping-Pong player, an excellent student) and seems to have some connection to an invisible world, sometimes in the form of a doppleganger. In GoGo Monster, as in Ping-Pong, the magical realism elements appear to be mostly in the mind of the Peko/Yuki character. Whether or not Super Star and the others are real, Yuki, Ganz and IQ all believe that they effect the world outside of Yuki's head. The art in this book is not quite as polished as in Sunny or Tekkonkinkreet (both of which I believe were published later?), but it's still engaging. If you're looking for a typical manga with this book, you'll probably be disappointed and/or bored as it's very long, very slow and very strange, despite the fairly mundane setting of a middle school.