The protagonist's job is to deliver letters, traveling between the human world and the underworld, delivering letters from the dead to living people (living people are limited to those with mental illness or Alzheimer's disease, etc.). While completing the work, he understands different stories and grows. Of course, he doesn't just deliver letters, he sometimes helps others deal with strange things happening in the world. The attack will appear later.
Intention: Be happy every day and be proactive