Transported to a different world for no reason!

I was summoned by a beautiful princess to help her kingdom defeat the demon king and save the human race, I was given a holy sword and was gifted with a powerful ability, I ventured into this new world, experienced new things, overcame hard trials, gained many friends who helped me in my quest. After defeating the demon king, I lived a happy life with my harem in another world. YEAH RIGHT!!!, like that would happen, this is the story of a man after being abruptly transported to a different world torn apart and ravaged by war between the races.