Why did the One-Punch Man anime change studios?
Season 1 was Madhouse at full strength. Season 2 was a different studio, a different director, and a visibly different show.
The first season of One-Punch Man aired from October 5 to December 21, 2015, made by Madhouse under director Shingo Natsume, and it was received as a landmark action production. On September 25, 2017, the production announced a new home for season 2: J.C.Staff would animate it, with Chikara Sakurai directing in Natsume’s place. The writer, character designer, and composer carried over; the studio and director did not.
THE TWO SEASONS
What changed on screenSeason 1: Madhouse, 2015
Twelve episodes, preceded by a preview screening in Saitama City on September 6, 2015. Critics treated it as a reference point for TV action animation; its review scores, including a 100% rating on Rotten Tomatoes from its first reviews, made it the season’s flagship.
Season 2: J.C.Staff, 2019
A recap special aired April 3, 2019, and the season ran April 10 to July 3, 2019. The reception inverted: reviewers singled out flat animation, rushed pacing, and a metallic sheen on the characters, and scores fell sharply from the first season’s.
No single announced reason
The production never published a detailed explanation for the change. What the record shows is the announcement itself, the staff list that stayed, and the two names that did not. Anything beyond that is speculation, and this page does not speculate.
Season 3 stayed
When season 3 came, it stayed with J.C.Staff, under director Shinpei Nagai. Whatever the second season’s reception, the production committee kept its studio.