This is the only TV anime series ever directed by Satoshi Kon, who is otherwise known for his feature films.

Satoshi Kon created the series to recycle an abundance of unused ideas that he had developed during the making of his previous three films (Perfect Blue, Millennium Actress, and Tokyo Godfathers) but which did not fit into those projects.

Kon said he wanted a format allowing more flexibility than feature films, where he worked for two and a half years in the same mood and method, so he chose a TV series to instantly realize ideas as they came to him.

Many characters' Japanese surnames are puns on animal names that match creatures they are depicted as in the 'Prophetic Vision' segments and the episode 'The Holy Warrior': Sagi (heron), Kawazu (frog), Ushi (cow), Tai (sea bream), Chō (butterfly, also hinting at her split personality), and Hiru (leech).

Episodes 8 through 10 are self-contained side stories that do not directly intersect with the main plot, focusing instead on other people affected by the Lil' Slugger phenomenon.

In the opening credits, all the characters are depicted laughing, a choice made both for its unsettling effect and because a repeating 'laughing' animation cycle was cheaper and required less work for the key animators.

In October 2006, all 13 episodes were screened in one overnight marathon (with three breaks) at TOHO Cinemas Roppongi Hills as part of a Satoshi Kon retrospective at the 19th Tokyo International Film Festival, the same event where Kon's film Paprika had its Japanese premiere.

In December 2009, Japanese director Takashi Shimizu announced plans for a live-action or film adaptation of the series, but the project ultimately fell through and no film was ever made.

The score, opening theme 'Dream Island Obsessional Park' and ending theme 'White Hill - Maromi's Theme' were all composed and performed by Japanese electronica musician Susumu Hirasawa.

The series holds a rare 100% approval rating on Rotten Tomatoes based on 13 critic reviews, with an average rating of 7.7/10, and was one of the Jury Recommended Works in the Animation Division at the 8th Japan Media Arts Festival in 2004.