Tribe Conquest: Harem starts in a tribe!

Eric, a man from earth gets transmigrated into the body of the weakest male of a warrior tribe, Buan Vila. Buan is the son of the patriarch, but his father is already dead with no one to protect the new host of his body. Eric now has to survive in this tribe of warriors while taking care of his stepmother and stepsister, who depends on him. But to help him, a system like spell awakens. Will he be able to survive while controlling his forbidden desires towards his seductive stepmother?