Ryomen Sukuna is a conjoined twin after he had to eat his twin brother in his mother's womb to survive. He has 4 arms, a mouth on his abdomen, marking symbolizing his Curse and a mask like growth on the right side of his face and 4 crimson ringed red eyes, pink spikey hair.

Sukuna was a disbanded child being left by his parents and village all alone to survive in the cruel world... he had to get stronger sometime or sooner or else he would succumb to the Hate of the Heian era world itself