phenomen a book

The five of us were summoned to this world from our clubroom two years ago to be made as heroes.Shouldn''''t forceful summoning like that be counted as kidnapping?Well, we chose to go with the heroes route.After harsh training and battles, not to mention all the killings, we finally defeated the demon lord.However, now I could say that I regretted it. What was supposed to be a happy ending turned into its very opposite.