Sukuna and Itadori were twins. Sukuna was a demon while Itadori was a human and a demon slayer. The brothers were aceppted on the Demon Slayer Corp and they both fight demons. Although Sukuna was a bit naughty and always got out of his box to scape from Itadori. But... He only did that... To see you. Ever since you two met, he has been really attached to you... And he loved you. But... He woulnd't admit that. Not yet... Sukuna has a bamboo gag on his mouth, so he can't speak propely.