Alright, the long version.
In the 1990's or in the 2000's, an archaeologist working at a top secret facility discovers his team unearthed a fossil of an alien/dinosaur from the dawn of history that hadn't been discovered before. He is shot by an associate and his blood spills on the fossil, which wasn't really a fossil but was a sleeping alien/dinosaur that has magical powers. It grants contracts to people at great prices. So its contract with the archaeologist was to take his body, but the archaeologist would survive. Both of them get trapped in the fossil and are frozen up.
Many, many, many centuries later, a group of biologists uncover the frozen man/alien god fusion they nickname "Iceman". Humanity can no longer live on the surface because they are genetically deficient, having hid out underground after nuclear fallout destroyed the surface initially. The scientists make a race of human/animal hybrids based on the iceman's DNA, he falls in love with one, escapes to the surface, the scientists use Avu Kamu to reclaim him and kill the specimen. He transforms into the true form of the alien/god and turns everyone into jellies. He then goes back to sleep.
More centuries pass and an Onikayumi scholar named Dii discovers the body of the iceman, and asks for a contract. He gets one half of the alien/god's mind and the two fight each other, with the white version of the alien/god badly injured. He walks through a forest and hears Eruru cry out for someone to save the dying Aruru. He then forms a contract with her and saves Aruru's life, becoming Hakuoro.
At the end, the two halfs of the alien/god reform and the alien is put back to sleep, since whenever it wakes up it causes problems for people (since that's what it does, grant wishes, and the wishes do bad stuff).