Every night, monsters begin to appear, eroding the daily life of Tokyo--. Office worker Shizuka Goto finds herself on the verge of losing her life to a mysterious man, but is guided by the "Night Guide (Ruby: Guidance)" and gains powerful skills. With her ultra-positive mindset, Goto enjoys enhancing her abilities like a game while battling monsters daily, preparing for the apocalypse with powerful equipment and the cooperation of the police. However, the monsters continue to increase in number and strength, and Goto must confront an unprecedented formidable enemy that has appeared in Shibuya to save her former colleague, Chigusa Amaryu…!