Humanity Has Declined

Humanity Has Declined (人類は衰退しました), or Jintai (人退) for short, is a Japanese light novel series written by Romeo Tanaka. The novels originally featured illustrations by Tōru Yamasaki for the first six volumes, but Yamasaki was replaced by Sunaho Tobe in 2011. Shogakukan published 11 volumes from May 2007 to September 2016. Three manga adaptations have been produced. An anime adaptation produced by AIC A.S.T.A., directed by Seiji Kishi, and written by Makoto Uezu aired in Japan between July and September 2012. Sentai Filmworks has licensed the anime in North America.

Plot
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.

Characters

 * Protagonist (主人公)
 * Generally referred to as either "I" (わたし) or "Ms. Sweets" (お菓子ちゃん), the heroine is a sensible mediator between humankind and the fairies. She is one of the few humans left capable of creating sweets, which causes the fairies to naturally flock to her. Having observed the slow decline of humanity, her outlook on life is grim.
 * Generally referred to as either "I" (わたし) or "Ms. Sweets" (お菓子ちゃん), the heroine is a sensible mediator between humankind and the fairies. She is one of the few humans left capable of creating sweets, which causes the fairies to naturally flock to her. Having observed the slow decline of humanity, her outlook on life is grim.


 * Grandfather (祖父)
 * The protagonist's grandfather, a researcher and firearm fanatic. Thanks to the fairies, he met with his granddaughter when he was 13 years old and a time paradox was created.
 * The protagonist's grandfather, a researcher and firearm fanatic. Thanks to the fairies, he met with his granddaughter when he was 13 years old and a time paradox was created.


 * Assistant (助手さん)
 * A young boy in a Hawaiian shirt who almost never speaks and serves as the protagonist's assistant.
 * A young boy in a Hawaiian shirt who almost never speaks and serves as the protagonist's assistant.


 * The Fairies (妖精さん)
 * They are mysterious beings with advanced technology that could be called magic. The fairies have permanent smiles on their faces and very literal, honest viewpoints on everything. Despite their cute appearance, they seem to have a total disregard for human safety. The presence of many fairies is supposed to increase one's fortunes, but they cause potentially fatal situations. They often request sweets from the protagonist in exchange for their assistance.
 * They are mysterious beings with advanced technology that could be called magic. The fairies have permanent smiles on their faces and very literal, honest viewpoints on everything. Despite their cute appearance, they seem to have a total disregard for human safety. The presence of many fairies is supposed to increase one's fortunes, but they cause potentially fatal situations. They often request sweets from the protagonist in exchange for their assistance.


 * Y
 * An old classmate of the protagonist's whose job is to identify human artifacts. She discovers a yaoi doujinishi from our era, however, and then spends her time self-publishing yaoi doujinshi.
 * An old classmate of the protagonist's whose job is to identify human artifacts. She discovers a yaoi doujinishi from our era, however, and then spends her time self-publishing yaoi doujinshi.


 * Pion/P-ko (ぴおん/P子)
 * A humanoid robot with cat ears. She makes sound effects whenever she acknowledges something of interest. Her original name is "Pioneer".
 * A humanoid robot with cat ears. She makes sound effects whenever she acknowledges something of interest. Her original name is "Pioneer".


 * Oyage/O-taro (おやげ/O太郎)
 * Pion's partner, who she is searching for. His original name is "Voyager".
 * Pion's partner, who she is searching for. His original name is "Voyager".


 * Curly (巻き毛)
 * The protagonist's classmate from her school days, who is disturbingly affectionate.
 * The protagonist's classmate from her school days, who is disturbingly affectionate.

Light novels
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 Bunko imprint; 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.

Manga
One chapter of a manga adaptation, illustrated by Rei Neyuki, was published in Shogakukan's Monthly Ikki magazine on January 25, 2010; however, the manga went on an indefinite hiatus and was ultimately cancelled. Another manga, illustrated by Takuya Mitomi, titled Jinrui wa Suitai Shimashita: Nonbirishita Hōkoku (人類は衰退しました のんびりした報告), was serialized in the same magazine from November 25, 2011, to May 25, 2012. Its chapters were collected in a single volume, released on July 30, 2012.

Mitomi also illustrated the four-panel comic strip manga Jinrui wa Suitai Shimashita: Nonbirishita Hōkoku 4-koma (人類は衰退しました　のんびりした4コマ), was serialized in Monthly Ikki from June 25 to August 25, 2012. A manga illustrated by Terae Kichijō and titled Jinrui wa Suitai Shimashita: Yōsei, Shimasu ka? (人類は衰退しました ようせい、しますか?) was serialized in Media Factory's Monthly Comic Alive between January 27, 2012, and January 27, 2013. 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" (リアルワールド) by Nano Ripe and the ending theme is "Yume no Naka no Watashi no Yume" (ユメのなかノわたしのユメ) by Masumi Itō. Sentai Filmworks has licensed the series for subtitled BD/DVD release in North America in December 2013.

Episodes

 * Bonus episodes