Rimuru continues with preparations for Walpurgis, including making Treyni evolve into a Dryas Doll Dryad. Meanwhile, Benimaru and his forces have arrived in Eurazania via transport magic, and they promptly run Clayman's army into a trap set by Geld. The Three Beastketeers, determined to rescue Carrion, set out to subdue the enemy army's leader. Albis fights one-on-one with Yamza of the Five Fingers, while Phobio takes on Footman and Tear.

Rimuru backs Clayman into a corner trying to get him to reveal who he's working for, but even on death's door, Clayman's lips are sealed. Left with no other choice, Rimuru finishes Clayman off. With Clayman dead and Carrion and Frey announcing that they're stepping down as Demon Lords, the total number of Demon Lords including Rimuru is reduced from ten to eight. Guy coerces Rimuru into coming up with a new name for their group, and Rimuru's solution is "Octagram," representing each of the Demon Lords as an eight-pointed star. Thus a slime became one of the eight Demon Lords, marking the start of a new age.