人類は衰退しました, lit. Humanity Has Declined, abbreviated as Jintai (人退)
A 2007-2011 light novel series by Tanaka Romeo that was published by Shougakukan's Gagaga Bunko imprint, with illustrations by Yamasaki Tooru, who was replaced by Tobe Sunaho in 2011. Also adapted into a Summer 2012 anime by AIC, a one-chapter manga that was cancelled by Neyuki Rei in 2010, a serialization in Shougakukan's Monthly Ikki, a 2012-current manga in Monthly Ikki by Mitomi Takuya, and another 2012-current manga in Media Factory's Monthly Comic Alive.
- Watashi (aka Main Character (主人公, Shujinkou), Ms. Sweets (お菓子ちゃん, Okashi-chan), a technically nameless protagonist
- Joshu-san, lit. assistant
- Pion (aka P-ko)