The Demon Queen is a pacifist?

The demon queen a vicious monster that is said to be cruel,evil and be extremely strong. I was summoned here by a goddess called Risa to kill the demon queen and after that I will go return to earth. In this world demons and humans have been fighting for years and years but because demons have started to become more technologically advanced I was summoned as the humans trump card. After 5 years of training and defeating the demon queen's generals I finally got to the grand finale the demon queen. Today I will enter her lair and put an end to this war once and for all.