While some manga languish for years without a proper English translation — let alone an anime adaptation — the runaway popularity of Demon Slayer: Kimetsu no Yaiba more or less ensured that Jump would move quickly to expand the franchise. Anime studio Ufotable announced that they were working on the television adaptation in the June 4, 2018 issue of Weekly Shonen Jump, and the first episode was broadcast in Japan on April 6, 2019.
The Demon Slayer TV series ended its initial run with episode 26, which aired on September 28, 2019. That same day, Ufotable announced that a follow-up feature, Demon Slayer the Movie: Mugen Train, was already in the works. The film made its major theatrical debut in Japan, on October 16, 2020 (via Monsters and Critics), and boy did it make a splash. The action-packed anime smashed the nearly two-decade-old box office record set by Studio Ghibli's Spirited Away, and became the fastest film to gross 10 billion yen by a fair margin.
While Mugen Train locked up a Japanese distributor early in Aniplex and Toho, English-speaking fans were concerned the animated feature might not receive the same theatrical treatment on this side of the Pacific. Fortunately, Funimation Films stepped up to distribute the feature in the U.S. alongside Aniplex of America, and the two companies have promised a theatrical release some time in 2021 (via Anime News Network). Given the breakout success at the Japanese box office, don't be surprised if Aniplex of America is eager to get this one into as many U.S. theaters as possible.
Because of the COVID-19 pandemic currently hampering the reopening of U.S. theaters, there's a chance this promised release window will change, but here's hoping 2021 is a better year for movie theaters.