Kaina Mochirugi, an office worker, was awakened from her sleep by an unfamiliar voice saying, "You have been reconstructed from a fossil." Exhausted from her work, a stuffed animal-like creature appeared before her. The creature, calling itself the "Hill Tribe," reconstructed her as one of the violent humans who died out 30,000 years ago, in order to make her fight against the "Ma Tribe," which threatened them. Kaina is bewildered, but she can't resist the cuteness of the "Hill Tribe" and strokes it. Then it is discovered that the "petting" has a dangerous power.