This story takes place before Rimuru's reincarnation. Shizu, also known as the Conqueror of Flames, responds to an urgent request calling her to the Kingdom of Filtwood. When she reaches the castle, many adventurers are already there. What request could have demanded such a huge gathering? It turns out a demon has been revived, and the adventurers have been called to subjugate it. It is said that more than ten of the most skilled adventurers have already been killed by this demon. But there is more to this request than meets the eye...
That demon was powerful, 
but he disappointed me, in the end.
كان ذلك الشّيطان قويّاً، لكنّه خيّب
أملي في النّهاية
Der Dämon war zwar stark,
aber am Ende war er eine Enttäuschung.
Ese demonio era muy poderoso,
pero al final me decepcionó.
Ese demonio era muy poderoso,
pero al final me decepcionó.
Ce démon était assez doué,
Quel diavolo non era male, 
ma alla fine mi ha deluso.
Aquele demônio até que era poderoso,
mas me desapontou no final.
Демон был довольно сильный,
но сгинул бесславно.