Yosui Inoue's（井上陽水） biggest hit in his 44-year-long career, "Shonen Jidai" (Childhood Days) is also his most heartwarming song. Every time I hear it, the song just brings images of summer days and young boys chasing butterflies in the countryside. If that sounds sappy....well, it is. One can squeeze a couple of litres of the old sentimentalism from the song with Inoue's tender vocals and the strings. And if there's one thing the Japanese love, it's the old days, no matter which generation.
Inoue's drinking buddy, the late manga artist Fujio A. Fujiko（藤子不二雄A）, had asked him to create a song at around the same time that Fujiko's 1978 creation of the same name was to be made into a motion picture. He even hummed a part of the melody that he wanted incorporated to help Inoue out, although according to J-Wiki, it was far from an easy task for the singer-songwriter. Strangely enough, the song had been intended to be sung by Yoko Oginome（荻野目洋子） as a B-side to her 1990 single, "Gallery", but with "Shonen Jidai" the movie coming out in the same year and the powers-that-be recognizing the quality of the song, Inoue sang it himself as the theme song for that movie.
At the time of its release in September 1990 though, Inoue's 28th single didn't exactly light up the charts as it stalled around No. 20. However, the following year when "Shonen Jidai" was then used for a Sony Handycam commercial, the song got a big boost, peaking at No. 4. It didn't hurt either when it was also used as the ending theme for a domino-effect segment on a TBS entertainment show called "Gimme a Break". By the end of 1991, it managed to become the 25th-ranked song of the year and continued to hang on to the end of 1992, becoming the 46th-ranked song. It was very much a slow-and-steady progression as "Shonen Jidai" finally hit the million barrier in 1997.
Shinji Kawahara（川原伸司）, under one of his pen names as Natsumi Hirai, helped out in the composition, and during recording, fellow singer-songwriter Takao Kisugi（来生たかお） was on the piano....as he is in the video just above. And in the years since, "Shonen Jidai" has been covered by everyone from Hiromi Iwasaki（岩崎宏美） to Sing Like Talking's Chikuzen Sato（佐藤竹善） to Hikaru Utada（宇多田ヒカル）.
The above is Utada's cover.
And this is the trailer for the movie, "Shonen Jidai".