The original manga ran from 1962-1969, and received several TV anime adaptations in the 60’s and 80’s.
The staff also released a new teaser visual for this third season as well.
It is based on the late Fujio Akatsuka’s original Osomatsu-kun manga, which features the Matsuno siblings as kids, and are all in love with the same girl.
Mr. Osomatsu follows the Matsuno Sextuplets as adults.