began as a single novel by Takimoto with a cover illustration by Yoshitoshi ABe, which was published by Kadokawa Shoten on January 28, 2002 (and on English in 2007).
[citation needed] The story was later adapted as a manga series, also written by Takimoto, with art by Kendi Oiwa.
The manga began serialization on June 24, 2004 in the magazine Shōnen Ace, also published by Kadokawa Shoten.
In the first afterword, dated December 2001, he stated that he was a hikikomori and was still recovering: "the themes addressed in this story are not things of the past for me but currently active problems."
Takimoto contributed a ~30 page story and part of a collaboratively written "relay novel" along with four other young writers.