A world unlimitedly similar to the present age.
However, this world was a world that coexists with intellectual life forms different from humans, called "elves".
When has elves evolved from when and when they differ from humans -
Why elves and humans, two intellectual life forms were born simultaneously -
The study to explore the mystery was called "elf study".
The hero, father of Takumi Kirihara, Ryutaro Kirihara is a leading expert on the research of elf science at university.
For this reason, the Kirihara family lives together with a woman elf.
Her name is Sophia, Ardis, Fairgrin.