Ahhhh, yes.....young, beautiful and urban folk traipsing around Tokyo in their Kelvin Thermos. And that song. That was "Niji no Miyako e"(To The Metropolis of Rainbows) by Hiroshi Takano（高野寛）. Originally, the song was meant to be just that 30-second jingle for Mizuno, but being played for 6 months during "Nelton Club" helped it evolve to single status and get it released in February 1990. No surprise there....it just had this infectious refrain that got me awake after 11 p.m.
Written and composed by Shizuoka-born Takano, I don't consider "Niji no Miyako e" as a technopop tune, but there is enough of a happy synthesizer in there that reminds me a bit of the ol' Yellow Magic Orchestra. Not surprisingly, according to the J-Wiki writeup, YMO is listed as one of Takano's influences along with The Beatles, late rocker Kiyoshiro Imawano（忌野清志郎）and American musician Todd Rundgren. In fact, Rundgren was also responsible for the production of this song.
"Niji no Miyako e"was Takano's 4th single and his most successful song. It peaked at No. 2.