Cheng Rui lived the retirement life of an elderly person at the age of 23, but unexpectedly met a little girl looking for a key during a walk. He got a mirror and entered a strange place through the mirror. He needed to complete the main task to survive.
Little girl: Little brother, from now on I will be your reality system~ Cheng Rui: No need to
Purpose: Pass through another world in the mirror, clear the dungeon, and save your life