"J.Boy" (i.e. Japanese Boy) was a title track from his 11th studio album released in September 1986. He headed overseas to the US to do the mixing part of the production, where he worked with two artists he wanted to meet for a long time: Jackson Browne and Don Henley. The album peaked at No.1 on Oricon weeklies and became the 21st-ranked album of the year with 419,000 copies sold for the first issue. The two CD re-issues have also charted well thanks to Hamada's new-found surge in popularity during the early-90's. He couldn't have picked a better title track to headline the album, as "J.Boy" is a fantastic number of grand proportions that is meant to be played in an arena concert. It's also got striking lyrics which go hand-in-hand with the music. Huge thanks to J-Canuck for providing the following translation for "J.Boy" and helping me magnify the content. I must say, we're doing pretty well with J-names here.
According to J-Wiki, Hamada designed the title to mean "not yet grown Japan". Hence the "boy" part. The protagonist of this song and the album is the same figure that appeared in Hamada's previous album Down By The Mainstreet (1984) as much younger boy, and now he was undergoing a transition towards adulthood as he was figuring out his purpose in life while dealing with all the surrounding mess. This transformation would be more-or-less complete in the following album Father's Son (1988). As for the "Japan" part, Hamada just seemed skeptical about Japan's bubble economy, which he thought was expanding too fast for its own good, especially within such a small territory. I'll let you interpret that comment however you wish. Or you can just simply appreciate the song for its introspective message about finding freedom within oneself.