I Was Summoned To Another World Just To Find Out The Sad Truth About This World

Ren is your typical college student in his sixth semester, he was living a normal life when suddenly one night he was summoned to another world to defeat the demon lord and kill all of demons in that world. After some times living in that world he finally able to meet the demon lord after that moment his view about this world change. will ren stay kill the demon lord and the rest of demons or will he do another things to fix this world?