Demon Slayer: Mugen Train topped box offices around the world. Here's how the anime film became one of the highest-grossing movies of 2020.

Demon Slayer: Mugen Train took the box office by storm with its 2020 release, earning it a spot at the top of Japan's box office. Beginning in October 2020, the film made $100 million in just 10 days, becoming the first movie in Japan to ever hit that mark. By the end of the year, Mugen Train was the fourth highest-grossing movie worldwide. So how did an R-rated anime film cause such a buzz?

Mugen Train is a continuation of Demon Slayer season 1. At the end of season 1, Tanjiro, Nezuko, Zenitsu, and Inosuke were all given a new mission; board the Mugen Train where 40 Demon Slayers had gone missing and slay the demon that resides there. In Mugen Train, the team joins forces with Kyōjurō Rengoku, the Flame Hashira. While on the train, the Slayers encounter the antagonist Enmu, Lower Rank One of the Twelve Kizuki. Together, the team has to work to slay Enmu and save the innocent civilians on the train, all while protecting themselves and their allies from danger.

Mugen Train was an immediate success in the box office. By December, the Demon Slayer movie earned $313.9 million, placing it at the top of Japan's all-time box office rankings. The movie even displaced Hayao Miyazaki's beloved Spirited Away, which had held the title since 2001. The movie has a near-perfect score on Rotten Tomatoes - 98% - and has been highly regarded by critics. The film debuted in the US in April 2021, putting its total earnings over $500 million worldwide.

There are multiple factors at play with Mugen Train's success. The first is the fact that Demon Slayer is wildly popular. The Demon Slayer anime is adapted from a manga of the same name, which topped the charts in Japan in 2020. The series' popularity only increased with the adaptation, quickly becoming one of the most popular contemporary anime series with fans around the world. Demon Slayer has been praised for its incredible animation, beautifully composed fight scenes, and intricate stories and characters.

Mugen Train was also released at an opportune time. The movie was released just as theater restrictions were lifting in Japan, meaning fans were eager to get out and take part in one of the first anime events since the pandemic hit. At the time, Hollywood was producing very little if anything at all, so Mugen Train had no competitions in the theaters. Some theaters in Japan were playing the movie as much as 40 times a day. Because Mugen Train takes place after season 1, it's considered required watching ahead of Demon Slayer season 2's release, which picks up in the Entertainment District arc. Despite the fact that its placement after season 1 makes the movie prohibitive to new fans, Mugen Train certainly wasn't hurting for audiences in the theaters.

Demon Slayer: Mugen Train is now available to stream on Funimation, Apple TV, Amazon Prime, and more.

Next: Why Demon Slayer's Inosuke Wears A Pig's Head