Humanity Has Declined is set in a post-apocalyptic world where the human civilization has regressed and humanity keeps decreasing in numbers. The story follows an unnamed girl who acts as a mediator between humanity and the "fairies" who are small elf-like creatures attracted by sweets and happy things, but also have the habit to cause trouble to her with their powers in their endless search for amusement.
Humanity Has Declined began as a light novel series written by Romeo Tanaka. Shogakukan published 11 volumes between May 24, 2007 and September 16, 2016 under their Gagaga Bunkoimprint; nine comprise the main story, while the other two are short story collections. For the first six volumes, the novels featured illustrations by Tōru Yamasaki, but he was replaced by Sunaho Tobe in 2011. Shogakukan republished the novels with Tobe's illustrations between November 18, 2011 and March 16, 2012. The novels are published in Taiwan by Sharp Point Press.
Volume list
Manga
One chapter of a manga adaptation, illustrated by Rei Neyuki, was published in the March 2010 issue of Shogakukan's Monthly Ikki magazine. It was announced in the May 2010 issue that the manga had gone on an indefinite hiatus and was ultimately cancelled. Another manga, illustrated by Takuya Mitomi and titled Jinrui wa Suitai Shimashita: Nonbirishita Hōkoku, was serialized between the January and July 2012 issues of Monthly Ikki. A single tankōbon volume for Nonbirishita Hōkoku was released on July 30, 2012. Mitomi also illustrated the four-panelcomic strip manga Jinrui wa Suitai Shimashita: Nonbirishita Hōkoku 4-koma, which began serialized in the August 2012 issue of Monthly Ikki and ended in March 2013 issue. A manga illustrated by Terae Kichijō and titled Jinrui wa Suitai Shimashita: Yōsei, Shimasu ka? was serialized between January 27, 2012 and January 26, 2013 in Media Factory's Monthly Comic Alive. Three compiled volumes have been released.
Anime
An anime television series adaptation produced by AIC A.S.T.A. and directed by Seiji Kishi aired in Japan between July 2 and September 17, 2012; it was also simulcast by Crunchyroll. The screenplay was written by Makoto Uezu, and the chief animation director Kyūta Sakai based the character design used in the anime on Sunaho Tobe's original concepts. Six bonus episodes were included on the Blu-ray Disc and DVD releases. The opening theme is "Real World" by Nano Ripe and the ending theme is "Yume no Naka no Watashi no Yume" by Masumi Itō. Sentai Filmworks has licensed the series for subtitled BD/DVD release in North America in December 2013.
