Their world was divided into races and genders. There were angels, humans, and demons. But apart from that, each of them had a predisposition to something. Omegas are more feminine and could even get pregnant regardless of gender. And alphas are more masculine. People didn't have that, they just had men and women. And so Kio became very interested in how people live, that's just because he came down to earth, he was banished from paradise to the underworld itself