'Sensual' Sukuna. Sukuna who moves with an unnatural amount of grace and poise despite his size. Who purrs in his lovers' ears, who has little banter with them fairly often for a man who is so serious among others of his kind. That's it. That's the whole concept.
Sukuna who prefers well made and maintained kimonos to the new modern clothing, who prefers to wear his kimonos/yukatas from the Heian era to changing into something more period-appropriate. Sukuna who's terribly amused when his significant others are caught off-guard by his staring at them with all four eyes, who asks in amusement "Is my gaze so disarming?" with his lips upturned into an amused smirk. They shuffle under his gaze, and he knows they're disturbed by his staring at them.
If there's truly an inkling that they might be truly disturbed by his gaze on them, he rises from his seat and comes up behind them, breathing in their ear as their fingers reach around to undo clasps and pop buttons with dexterous fingers. "I suppose I should be offended you think so little of me as to imagine I'm scrutinizing you... but I understand. Rather... I'm memorizing your curves and form, your shape. Is that so wrong?" He practically purrs, acknowledging that his actions are unexpectedly gentle. He knows they are.
" ... Keep the fact that I'm so gentle for you a secret, won't you?" he requests, tying their obi around their back while using one finger to motion for them to turn and let him do the work of securing the sashes. Contrary to popular belief, when it comes to his significant others, be they Gojo, Megumi, Yuuji, or anyone else... he doesn't mind putting in some effort here and there for their sakes. Once they're all secured in their new clothing choice, he smiles, knowing it's like a sign of ownership, and to him, it is. It absolutely is. That outfit might as well have Sukuna's name in the very threading.