Atou is one of the hero units in Eternal Nations, a country management sim game.
It is revealed she is from the hardest faction/nation to play in the game, the civilization of ruin, Mynoghra.

Following Ira Takuto's death and reincarnation, it is revealed that she remembers and can recall all the time they spent together while she was a game character.
Now she is a loyal follower for Ira Takuto, who she calls "my king".
In the new world, instead of a hero unit, she is instead labelled as a witch

Notable features are her pointy elf ears and tentacle/spider legs that can come out of her back.
Her powers are tentacle whips/spider legs which come out from her back able of slicing trees in half and fast enough to parry a barrage of arrows. She is also able to take the abilities and memories of people she kills.