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...
Much time has passed since
I came to the living world.
مضى وقتٌ طويل منذ أتيت إلى عالم الأحياء هذا
Was ist es lange her,
dass ich auf Erden wandelte?
Hace mucho que no vengo a este mundo.
Hacía mucho que no venía a este mundo.
Oh, da quanto tempo 
non mi trovavo nel mondo dei vivi!
Voltei a este mundo após tanto tempo...