(妄想代理人, Mōsō Dairinin
?) is a Japanese anime television miniseries about a social phenomenon in Musashino, Tokyo caused by a juvenile serial assailant named Lil' Slugger (Shōnen Bat, or Bat Boy in the original Japanese version). The plot relays between a large cast of people affected in some way by the phenomenon; usually Lil' Slugger's victims or the detectives assigned to apprehend him. As each character becomes the focus of the story, details are revealed about their secret lives and the truth about Lil' Slugger.
It was created by Japanese director Satoshi Kon and produced by Madhouse.
The series first aired on Japan's WOWOW between February 2, 2004 and May 18, 2004. A series of four English dubbed and subtitled DVDs produced by New Generation Pictures were released in North America and Europe between October 26, 2004 and May 10, 2005 distributed by Geneon. A UMD version of Volume 1 was made available on October 10, 2005. The English dubbed version began airing in the U.S. on Cartoon Network's Adult Swim on May 28, 2005 followed by an encore airing that began on June 6, 2006. In Canada, it began a run on the digital channel G4TechTV Canada on July 27, 2007, at 8:00 p.m. ET/PT.