Ah, yes, Doraemon（ドラえもん）....took me several years to figure out that the famed manga/anime character was a robot cat from the future, but he and his buddies have been in my memories since I was an elementary school student. Born from the mind of the late manga artist, Fujiko F. Fujio（藤子・F・不二雄）in 1969, I remember reading my first manga of Doraemon as he helped his best friend, feckless student Nobita-kun out of his latest jam...I think what the earless cat robot pulled out of his TARDIS-like pocket that time was an instant hole which allegedly could allow the two to escape any bad situation (or Nobita's mom). Of course, the conclusion proved to be far less happier (funnier for the reader) when Doraemon and Nobita ended up crawling out of a stinky can of garbage after Mom innocently threw away the hole.
I didn't get to see my first episode of the anime adaptation until my graduation trip in 1981, though. I was spending the last two weeks of my trip with my relatives in Osaka and Wakayama Prefecture. And one of the things I remember during that leg of my vacation was staying with my uncle and aunt in the tiny apartment over their old stationery shop in Namba City. Incidentally, I caught Princess Di's and Prince Charles' epic wedding live on my relatives' TV, but with my cousins who were themselves elementary schoolers at the time I dropped on by (I was almost 16), we saw that episode of "Doraemon".
Of course, there was the cheerful and magical opening theme song that has become instantly recognizable to basically anyone in Japan (and beyond). Any adult would also probably revert to childhood again on hearing "Doraemon no Uta" (Doraemon's Song) as originally sung by anison legend Kumiko Ohsugi（大杉久美子）. It has that light marching beat that would most likely have the littlest of children start proudly strutting on the tatami whenever the show came on. I also got in on the act by actually singing the last couple of lines in Ohsugi's voice which caused no end of mirth for my cousins.
The song made its debut when TV Asahi's "Doraemon" debuted in April 1979. It was composed by Shunsuke Kikuchi（菊池俊輔）and written by Takumi Kusube（楠部工）. Kusube, who was only in his mid-teens at the time, has stated that the lyrics were a family effort; his father was Daikichiro Kusube（楠部大吉郎）, the president of Shin-Ei Animation（シンエイ動画）, the company that produced the show. Whoever was ultimately responsible for the words, there were shoutouts to the various wonderful things that came out of Doraemon's pocket such as the take-coputa（タケコプター...Bamboo Copter）and the dokedemo doa（どこでもドア...Everywhere Door）. And Doraemon himself (as played by Nobuyo Ohyama/大山のぶ代) would make a cameo in the song as well.
The song was a huge success as it became the No. 1 song of the year on the Oricon Anime/Children's Songs chart. Of course, it's been covered by a number of artists since its 1979 debut, one of them being Misato Watanabe（渡辺美里）in 2003.
In getting the information for this article, though, I found out that the 1979 anime hadn't been the first try at adapting the manga for the telly. In fact, "Doraemon" had its very first start on the visual medium via NTV's version in 1973 which lasted only a year. And the theme song, "Doraemon" was far different from "Doraemon no Uta" in terms of the melody. As sung by Harumi Naito（内藤はるみ）, it sounded like a kayo of a drunken spree on an izakaya-filled street...not that I'm lambasting the song. It was just a very different animal. Doraemon's creator, Fujiko himself came up with the lyrics while Nobuyoshi Koshibe（越部信義）composed the music.
The above video features the opening of the original NTV version of the show.