The Tatami Galaxy (四畳半神話大系) is a 2004 Japanese varsity novel written by Tomihiko Morimi and published by Ohta Publishing. Its first-person narrator is an unnamed upperclassman at Kyoto University reminiscing on the misadventures of his previous years of campus life, with each of the four chapters taking place in parallel universes in which he is enrolled in a different student society.
A sequel, The Tatami Time Machine Blues (四畳半タイムマシンブルース), was published in 2020, which combines the characters of The Tatami Galaxy with the plot of Makoto Ueda's play and film Summer Time Machine Blues. English translations of both novels were published by HarperCollins in December 2022 and November 2023, respectively.
The Tatami Galaxy was adapted into an 11-episode anime television series produced by Madhouse and directed by Masaaki Yuasa, which aired on Fuji TV's late-night Noitamina programming block in 2010. The adaptation was critically acclaimed, winning the 2010 Japan Media Arts Festival Grand Prize in the Animation Division and the 2011 Tokyo Anime Award in the Television Category. An original net animation adaptation of The Tatami Time Machine Blues produced by Science Saru premiered in September 2022 on Hulu in the United States and Disney+ internationally.