Ruin, a demon adventurer, was banished from the brave party as incompetent. Without being known for the shadow of the command tower ... However, the moment he finds Sasha, the Demon King of Death, one of the Seven Demon Kings sealed, he awakens to the Demon Lord who has the power to follow the Demon King !! -Ruin, who succeeded in drawing out the power of the Demon King with Sasha as a companion, begins to follow all the Demon Kings who are the cause of the conflict between humans and the demons. Overwhelming Musou fantasy by the boy who controls the Demon King, opening !!