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's why you can't judge how 
powerful your opponents are.
لهذا لا تستطيع أن تقيس قوّة خصومك
Deshalb erkennen sie
die Stärke des Gegners nicht.
Por eso no puedes juzgar
el poder de tus oponentes.
Por eso no puedes juzgar
el poder de tus oponentes.
que vous ne savez même pas
juger un adversaire.
Ed ecco il motivo per cui non riesci 
a comprendere quanto sia potente il tuo avversario.
É por isso que não consegue julgar
o poder de seu oponente.
А потому и не способны
оценить силу противника.