The so-called PET refers to a teenager with super powers who can change other people's memories. They are controlled by the underworld to achieve their ulterior motives. The leader of this group of "PETs" actually escaped from the underworld in order to save his companions. Humans have a lot of memories, but happy memories are piled up on the mountain, and unhappy memories are placed at the bottom of the valley. It is between the ups and downs of this valley that a person can exist. "PETs" who can modify other people's memories have established a trust relationship that exceeds that of family members with their own memories. Many times, memories can deceive people or even deceive themselves. We ourselves will inadvertently modify memories we don't like, at least to make ourselves feel that these memories are better.