Yayoi, a spunky high school girl, has inherited spiritual powers from her mother, and she uses these powers to protect people. During a fight with the devil Ura, Yayoi's power turns the devil into a black kitten. Now, even though Ura doesn't hide his desire to "eat" Yayoi's power when he gets the chance, they develop an interesting relationship: the two begin living together, and Yayoi takes her new feline "friend" on her adventures. (Source: Tokyopop)

Mugen Spiral was published in English by Tokyopop from January 9, 2007 to August 14, 2007, and again as a 2-in-1 omnibus by the same publisher on March 30, 2010.