Decay of Angels was a terrorist organization that has long since been hiding in Japan, operating as a murder association which possesses a single page from the Book. Mushitaro Oguri explains that the Decay has a fourfold scheme with the penultimate goal of eliminating the country, which they operate on by writing on both sides of the page. Their members are Nikolai Gogol, Fyodor Dostoevsky, Bram Stoker, and Sigma. Their leader is Fukichi Ouchi.