Doraemon is a popular and long running anime based upon the manga of the same name. Its best known adaptation originally ran from 1979 until 2005, while a reboot that began airing a month after the first series' conclusion is still airing to this day.
However, the very first attempt to adapt Doraemon to television had actually occurred in 1973, with a series produced by a company named NTV Video (previously known under the names of Japan Broadcast Film, and Tokyo TV Movie). It aired on the (unrelated) NTV network. The series was broadcast from April 1st 1973 until September 30th 1973, for 26 episodes. Each consisted of 2 segments, making the series 52 shorts in total.
While the series did well in the ratings and was considered to be extended for another year, it unfortunately encountered budget issues during its run, compounded by financial problems that the studio had, as well as the president of NTV Video abruptly resigning during the television run. The new president appeared to not regard the anime very highly, while the financial issues lead to the studio going bankrupt and being dissolved. Many of the staff that worked on the show wound up unpaid for their efforts due to this.
With the dissolution of NTV Video, the film reels to the series and other possessions wound up sold off to cover debt, while other belongings in the studio and production materials were either thrown out in the garbage or destroyed in a kerosene fire. It has been erroneously reported that NTV deliberately organized a "cremation" fire and destroyed all the episodes; however, the production chief Masami Jun (at the time credited under his real name, Hiroshi Shimosaki) has stated that this wasn't the case, and has gone on to attempt to debunk the misconceptions surrounding the series' production and fate. Even so, a significant portion of the anime can be considered lost to some degree.
In 1995, episodes 18, and 20 through 26 were found to be stored in Studio Rush (now known as IMAGICA), and other segments have been found, though 2 remain without their audio tracks. The opening and ending credits do still exist as well, along with a pilot film that was produced in 1972. These are occasionally shown at Doraemon fan conventions in Japan, but cannot be released legally on DVD owing to rights complications due to the production studio being defunct. Some episodes of the series also only survive in still image form. It is unknown what may have happened to the other reels.
This version was briefly rebroadcast in 1979, but was abruptly pulled off television by order of Shogakukan, who did not want the new adaptation's reputation to be affected by the existence of the previous one, or for child viewers to be confused at the two different versions. It is possible that recorded video from this time period may exist in some form.
While Hiroshi Fujimoto (aka "Fujiko F") was disappointed in the choice of studio to adapt Doraemon and the changes made to Nobita and Doraemon's characters, it is said that upon the closing of the NTV studio, he did not hold any hard feelings against the staff and expressed the hope that they could work on a new attempt at Doraemon in the future.