"Natsu no Owari no Harmony"(Summer's End Harmony) is about as bromantic as it gets. Anzen Chitai（安全地帯） lead vocal, Koji Tamaki（玉置浩二）, and his old buddy/boss/collaborator, Yosui Inoue（井上陽水）, got together in September 1986 to do this epic heartfelt duet; Inoue took care of the lyrics while Tamaki covered the music. You can almost hear the guys at karaoke just yelling "I LOVE YOU, MAN!"to each other near the coda. The ballad was also part of the large "Anzen Chitai V"album (already profiled).
And in fact, it was at my old haunt of Kuri where I first heard the song. Mind you, the word "bromance" was still decades from being born.