NisiOisin's Monogatari series novels began with Bakemonogatari in 2006. The "final season" of the novel ended with Zoku Owarimonogatari in September 2014, but presented the preview "Monogatari Series, next season Tsugimonogatari". Four spin-off novels - Orokamonogatari, Wazamonogatari, Nademonogatari and Musubimonogatari - released in 2015 and 2016. The new monster season was launched with the novel Shinobumonogatari in July 2017.
The novel series focuses on Koyomi Araragi, a lonely and unsuccessful student. One day, his classmate Hitagi Senjōgahara accidentally falls into his arms and discovers that Hitagi literally weighs nothing. According to her, she has had this problem since the first year of high school. After Koyomi helps her with her supernatural problem, Koyomi meets other girls who are worried about some form of supernatural "weirdness."