9-Nine is a Japanese adult visual novel series developed and published by Palette.

[1] An English version of the visual novels was released by Sekai Project from February 2019 to March 2021.

A manga adaptation with art by Izumi Kawachi has been serialized online via Futabasha's Gaugau Monster website since October 2021.

An anime television series adaptation produced by PRA, titled 9-Nine: Ruler's Crown, is set to premiere in 2025.

[3][4] The series, titled 9-Nine: Ruler's Crown, is produced by PRA and directed by Koichi Ohata, with characters designed by Saori Sakiguchi.