Newly recognized Demon Lord Rimuru Tempest opens the Tempest founding festival, a diplomatic showcase aimed at presenting his monster nation to the world and drawing in new citizens. Season 3 picks up directly after his ascension at the Walpurgis banquet as Rimuru navigates the expectations of other Demon Lords, a growing conflict with the Holy Kingdom of Ruberios, and an incoming confrontation with fellow otherworlder Hinata Sakaguchi.