Sasami

is an unknown assailant, who is affiliated to the Land of Rivers.

Personality
Sasami, like her older twin brother, is a very sadistic person, delighting in the suffering of others and likewise will taunt them with equal joy. She is also obsessed with power, delighting in the feel of increased might from her cursed seal. At the same time, she is a very alert individual, able to see through deception based on the nature of her opponent's movements.

Appearance
Sasami has long green hair, light grey eyes with thick eyebrows in the same colour as her hair, grey lipstick, and a pale complexion. Sasami wears a black and white kimono jacket with a belt, dark shorts and knee-length shinobi sandals. She also wears two yellow circlets around her head. She has a collar device based on cursed seals around her neck. When she uses her cursed seal, her skin takes a brown-grey tone, and her appearance takes a monstrous form, somewhat equine.

Jūgo Arc
Sasami and Momo confronted and prevented Team 15 from requesting backup from Konoha. They managed to immobilise Namida Suzumeno and Wasabi Izuno by using the opportunity to test their device based cursed seals while Sumire Kakei reluctantly escaped with Nue. They later disguised themselves as researchers from the Land of Rivers and brought Namida and Wasabi, both infected with the cursed seal, back to the village, informing Team 7 that they only found the two members of Team 15 unconscious but did not find Sumire.

After the Land of Rivers researchers took custody of the incapacitated Jūgo and the entire village turned against the Konoha-nin, she and her brother stood before Jūgo with the head researcher preparing to experiment on him. Later, after delighting in watching Wasabi Izuno and Namida Suzumeno's suffering from their cursed seals, Momo and Sasami were sent to search for the Konoha shinobi wandering in the forest. There, they noticed "Sumire" running by. The siblings quickly pursued her. During the chase, Sasami realised it was a diversion from how their target was deliberately staying just ahead of them. Momo then fell back to the base, while she went on ahead and encountered Sarada and Karin.

Once transformed, she quickly began making sport of her opponents, treating them as prey. Karin's sensory prowess and Sarada's Sharingan let them follow her movements enough to defend themselves. However, as Sarada's chakra continued to drain from overusing her dōjutsu, Sasami managed to land a powerful blow on her. Karin was able to subdue Sasami with her chakra chains long enough for Sarada to take some of Karin's chakra, letting her deliver a devastating punch that knocked Sasami out and destroyed her Cursed Seal collar.