There is a legendary place in the European Middle Ages where there is no daylight and is inhabited by elves. Their lifespan is only a hundred years, but a new life will be born from the holy spring every hundred years, so there is only one surviving elf. Each newly born elf bears an extremely important responsibility, guarding every plant and tree here, and inheriting the bloodline. This is the bloodline engraved in their bones, but if they meet the destined person, it will be a gift or a disaster.
Concept: Beautiful love