The "memory spore" theory that human memory has a physical form
- In the near future world, humans have discovered that memory is not just brain waves, but a microbial community called "spore crystals"
- These half-organic, half-mineral crystals multiply in the hippocampus of the brain, and their colors correspond to the type of memory (gold-happy/blue-sad/black-trauma)
- The special profession "Memory Agriculturist" can cultivate and harvest the memories of others to form a new drug "Memory Dust"
