The original Osomatsu-kun series followed the Matsuno brothers; Osomatsu, Karamatsu, Choromatsu, Ichimatsu, Jyushimatsu, and Todomatsu, who are all identical sextuplets who cause mischief.

Mr. Osomatsu depicts the brothers as being ten years older than their original counterparts (with the action taking place in a contemporary setting).

Outside of Japan, the series aired in simulcast on Crunchyroll; marking the first media in the Osomatsu franchise to receive an official English release.

[9][10] Additionally, the third episode, which features a crude parody of Anpanman, was edited for its BS Japan broadcast and is altered in its home video release.

[13] A second season was announced in April 2017,[14] having previously been teased in a listing for the Blu-ray release of "Mr. Osomatsu JRA Special 2016" (おそ松さん おうまでこばなし, Osomatsu-san Ouma de Kobanashi),[15] and aired between October 3, 2017 and March 27, 2018.

[16][17] An anime theatrical film for the franchise was announced in August 2018, with the main staff and cast from the television series returning to reprise their roles.

The series is animated by Point Pictures and directed by Tetsuya Endo, with Endo handling series scripts along with Hitomi Ogawa, Yūki Nagashima designing the characters based on FuRyu's original character designs, and Yukari Hashimoto returning to compose the music alongside Ruka Kawada, Tetsuya Shitara, and Yayoi Sekimukai.

[29] In Australia and New Zealand, Madman Entertainment released the first season on DVD on December 7, 2016,[30] and made the series available on AnimeLab.

A manga adaptation of Mr. Osomatsu, illustrated by Masako Shitara, began serialization in Shueisha's You magazine on January 15, 2016.

[39] A serialization focusing on the series' collaboration with the Ultraman franchise, Ultramatsu, is an ongoing manga published on LINE that takes place after the Season 1 finale.