The Reformation of the World as Overseen by a Realist Demon King, Vol. 6 (manga) [Paperback]

Now that Astaroth has already taken down the Demon Kings Sabnac and Eligos with the help of Eve, Hijikata Toshizou, and Jeanne dArc, hes set his sights on the star-shaped Demon King Decarabia. But even though Astaroths plan to turn Decarabias greed against him worked beautifully, the rival Demon King has a trick up his own sleeve. And when Decarabias castle does fall into Astaroths hands, hell need someone capable to run it&perhaps even one of the greatest strategists of all time!