The Tatami Galaxy

is a Japanese comedy-drama campus novel written by Tomihiko Morimi, originally published in December 2004 by Ohta Publishing in the tankōbon format and later reissued in March 2008 by Kadokawa Shoten as a bunkoban. Its first-person narrator is an unidentified upperclassman at a 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 university society. As of January 2011, Korean and Chinese translations have been published.

Plot
The story of The Tatami Galaxy follows an unnamed third year university student in Kyoto, Japan and what he views as his wasted time in a particular club (also called "circle") at his university. He meets Ozu, another student, whose encouragement sets him on a mission of dubious morality. He contemplates his affection for a second year engineering student, Akashi, and makes promises to her, usually of and within a romantic subtext. The culmination of his dubious missions often conflict with his interest in her in some way. The story is one of a number that draw on the author's experience in Kyoto University.