Yuuen and Emba are from rival tribes, so when Yuuen's tribe starts to fall behind in hunting, Yuuen's father has him dress as a woman to seduce Emba into sharing his spoils. It works, but Yuuen is wracked by guilt and jealousy over the trick. But Emba knew who Yuuen was all along, and he's not about to let him go. Chapter 4 includes the story of their fathers, Selem and Yuni, who also had a forbidden romance before deciding they couldn't go against the status quo, I guess. No trigger warnings.
Story 1-3 Yuuen and Emba, two different clans people who fall in love. A cute love story. Happy ending. Story 4: Unfulfilled love story between two different clans men. Side stories: Continuation of the Yuuen and Emba love story. Very cute.
Takashima's debut is possibly singlehandedly responsible for pioneering the caveman or "tribal" romance as a notable yaoi subgenre - where Japanese writers get to indulge Arcadian fantasies of loincloths and fig leaves and virile men in tasteful mesolithic nudity, and heady fever dreams of primal urges and mating rites. About as historically accurate as Conan the Barbarian, and just as entertaining.
They fell in love too quickly for my liking, but the fathers' story is just sad. I didn't cry or anything but in chapter 3 where it shows on his hand that he's still wearing the necklace (given to him chapter 4) but as a bracelet, that broke my heart.