Heaven is a place for good people; hell is a place for evil people. Both are illusory worlds created by humans, but they are real. We must know that heaven may not be good and hell may not be bad. Although this is a question that has no answer, it will be revealed one day.
In order to maintain "spiritual" peace in the world, two assassins from hell will be sent to the world to get rid of those evil spirits. They are the biggest assassination positions in hell: Sword Master and Messenger of Hell.
However, the Hell Messenger's life is only 500 years. The ultimate goal is to eliminate the evil spirit Kresia, and he will die in the end... Therefore, the Hell Messenger Mansilo must be the first born to perform tasks in the world, but he has experienced a lot in it and learned what love is, what family is, what feelings are, and what real "life" is.
However, time is always short, and there is only a short period of life left. I really want to continue to stay in the world. This is the so-called destiny\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ There is never enough time to finish what I want to do... I really want to... Live a human life.