The story is set in Raja, located to the west of Tempest. It used to be a flourishing nation thanks to its gold mines, but now there is no trace of the prosperity that once existed—the mines have poisoned the lake and the nation has fallen into dire states. Queen Towa used the magical power of her tiara, which has been passed down from generation to generation in the royal family, to remove the poison and protect her people. However, the magic comes at a cost. The curse that was cast upon the tiara has consumed her body and is eating away at her life. Amidst all of this, a survivor of the Ogres, Hiiro, suddenly appears in Tempest. He's supposedly Benimaru's older brother and tells them that his life was saved by Towa. Hiiro, who has come to Tempest to enlist the aid of Rimuru to help him save Raja and Towa, has a fateful reunion with Benimaru. Rimuru and friends make their way towards Raja to help the nation out from its crisis and unravel the mysteries surrounding Towa's curse, but they find themselves getting embroiled into an unbelievable conspiracy.

[Source: press release]