Koro Sensei Quest!

A spin-off of Assassination Classroom (Ansatsu Kyoushitsu). Aired in Japanese cinemas alongside Assassination Classroom the Movie: 365 Days‘ Time (Ansatsu Kyoushitsu Movie: 365-Nichi no Jikan), and later reused as episode 2 of the ONA series Koro-sensei Q!

Shorts of Ansatsu Kyoushitsu (TV) 2nd Season which adapt chapters of the manga which are not in the TV series. The adapted chapters are 78 ("Takebayashi no Jikan") and 79 ("Shihaisha no Jikan, Ni Jikanme"), which are published in the ninth manga volume.

Three kids are stuck in a strange city causing massive mayhem through the land. They are searching for an atypical rabbit in order to return home. Koto, the eldest of the three, seems to have some sort of connection to this weird place ruled by a monk, a demon, and a priest.

Mini anime for Chuuzenji-sensei Mononoke Kougiroku: Sensei ga Nazo wo Hodoite Shimau kara. released on YouTube.