He serves as an acquaintance and the archenemy of Osamu Dazai. Fyodor is the leader of an underground organization called the Rats in the House of the Dead, and is one of the five members of the Decay of the Angel, a terrorist organization plotting to wipe out all nations in the world. His goal is to find the reality altering book that's hidden deep within Yokohama to use it and rid the world of all its ability users. He has spectacular memory, amazing grammer and is very well spoken.