I was hoping anyone here might have some information on some lost pieces of Osomatsu-Kun related media. According to the Osomatsu Wiki, there was a pilot made for the 1988 series that focused more on the sextuplets than Iyami and Chibita, and was based on the first chapter of the original manga series. I can't find any information that verifies this, and the wiki doesn't cite their information, so I'm unsure if it actually exists. I did, however, find the original character set list that they described.
The other piece of lost Osomatsu-Kun related material is a special titled "Nyarome's Fun Mathematics Classroom". I can't find footage of this special, but this entry on a Broadcasting Library's website confirms that it does exist. The Osomatsu Wiki states that there were three segments, and none of them have gotten an official home video release, so they're all lost.
I have a hunch on where I might be able to find some sources on the Osomatsu-Kun pilot, but it would require me having to buy magazines from a specific time frame, and even then it's not 100% confirmed it will be in there. If anyone has anymore information, please let me know.