Eighteenth game of the Touhou series, thirteenth in the Windows generation, sixth spinoff overall, and third spinoff based on the mainstream danmaku format. Numbered "Touhou 12.8" and released 14 August 2010 at Comiket 78.
The game is based on the Touhou Sangetsusei manga series, with artwork by Sangetsusei artist Hirasaka Makoto, making the game the first collaborative spinoff not involving Tasogare Frontier.
In her first-ever protagonist role, Cirno declares war on the Three Mischievous Fairies - Luna Child, Sunny Milk and Star Sapphire - in their first in-game appearance.
