The Six Eyes were not the Sharingan.
Copying an opponent's abilities on the spot from scratch was what the Sharingan did over in Naruto. Although the Six Eyes lacked that effect, Chinatsu could still use the insight they granted, along with her own brain, to carve out a way to survive.
"So this is an Open Domain..."
With Simple Domain deployed and her body poised to draw a sword, Chinatsu raised her head and quietly studied the structure of Sukuna's Open Domain.
If she had an experience bar above her head, "EXP +1" notifications would undoubtedly have been popping up one after another.
Naturally, Sukuna had no intention of letting this thief steal his secrets. Keeping both hands in the sign for Domain Expansion, he actively aimed and unleashed the frenzied slashes within his domain.
"Time to end this."
As Sukuna grinned confidently, a deluge of slashes hurtled toward Chinatsu. Realizing he was actively aiming them at her, she immediately stopped maintaining Simple Domain and activated another secret art instead.
[Secret Art: Falling Blossom Emotion]!
Chinatsu shifted from her crouched sword-drawing stance into a special opening combat stance. When the slashes powerful enough to shred hardened steel struck her, they barely managed to leave a few wounds on her skin.
Unlike [True Shadow Style: Simple Domain], this was an alternative method of using cursed energy that only members of the Three Great Families of Jujutsu Society could learn.
It involved forming an extremely even, sensitive membrane of cursed energy over the body, then releasing cursed energy outward the instant an external attack struck it, reducing the attack's power through a mechanism akin to deflecting it.
Such a technique was utterly useless against a mental domain like Unlimited Void, but against Sukuna's straightforward, brute-force offensive domain, it played to its strengths