the world after death is a special space, and when a teenager who has regrets in his life dies, he will enter this space. When they get what they want, they will leave this space and enter reincarnation.
The creator of the space cannot be traced, nor can it be known where it exists. It may be born from the obsession of a certain person, but after that person dies, this space does not disappear.
-------About NPC---------------
This space is not accessible at any time, just a period of time, absorb a group, when this group gets what they want, get out In this space, the next batch will be absorbed.
But each batch has the last person left behind, and these people become NPCs.
This time, a special situation occurred, that is, the boy's so-called love, so the NPCs that were left behind disappeared.
--------About angel player------------- A
computer genius can compile such a powerful software. The main function of this software is to give a person the ability to create his own abilities. You can create your own abilities by modifying the program.
So, how did you choose who would play the angel?
It is not mentioned in the text.
-------About the first come and last arrival of Tachibana and Otonashi ----------------
Tachibana used Otonashi's heart, but did not prolong his life, he also entered this space.
Otonashi is slow, I don't understand this question either.
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