Sixteen years ago, twins Asa and Yuru were born in the secluded Higashi Village. While Yuru spends his days hunting animals and gathering provisions, Asa is forced to stay inside a cage, and only a select few are allowed to visit her. Although their parents abandoned them long ago, Yuru swears to stay and protect Asa as long as he lives.

One day, the primitive village is suddenly approached by helicopters and armed soldiers, who begin mercilessly executing the villagers. During the chaos, however, Yuru awakens the village's two protectors, Left and Right, who are his Daemons—supernatural beings made to serve their master. Furthermore, Yuru witnesses Asa being attacked by someone who resembles her. It turns out that the attacker is actually the real Asa, who fled the village with their parents.

As the conflict comes to a close, Yuru escapes the village alongside Left, Right, and Ryuu "Dera" Tadera, a Daemon retainer who is willing to help Yuru blend into the modern world he does not know. Realizing that his whole life so far has been a lie, Yuru sets out to find the real Asa once more with the help of his Daemons and Dera in order to reunite with his parents.