Saul placed his mind-body palm over Hisame's forehead. Genjutsu in the series had been shown to be capable of erasing memory, or at the very least blocking it from being remembered. Saul wanted to use this chance to try it out on Hisame.

He was becoming very experienced with leaving and influencing chakra memories within his own consciousness, the foundation of his Frontloading technique. Tampering with someone else's memory should be the same thing, except in reverse. Instead of continuously drawing on the memory and imbuing it with chakra, he instead had to disperse it until there were no traces left.

This would be too risky to test in Konoha. Kurenai was his sensei. Many knew about who he was and that he was learning Genjutsu. If his technique was sloppy enough for traces to be detected, they would lead straight back to him. Even if this ability of his was discovered from a benign reason like just testing it out, the village 'knowing' he had the ability to erase memories with Genjutsu would narrow down the trail to him if anything unsavory was discovered.

Valid practice was key. Normal people were too easily manipulated to serve as proper training, and Konoha ninjas were too connected to risk testing on. Nobodies with chakra like missing-nin, were the perfect targets. Saul entered Hisame's mind.

The space was filled with rage, sorrow, humiliation, and... suppressed desire? Saul chuckled. He followed the strong emotions, leading him to a scene. The area was lit with dim moonlight. Grass started to appear, crunching under his feet. Then trees formed as he walked, the area slowly coalescing into a replica of the scene he remembered but from a different perspective. 

"Interesting..."

The memory was an amalgamation of emotions, feelings, sights, smells, and thoughts, connected to many other places. Places like how she continuously tried her best to maintain her appearance, buying designer clothing like that impractical shirt she wore, or how much the fishnet bra that was ruined cost.

Vanity and Self worth were everything to her. He had taken everything she stood for, pushed it aside, and violated her forcibly. Yet she couldn't reconcile that with the feelings of humiliating pleasure it brought. She was disgusted with him and herself. It was sure to become an incredibly traumatic memory where she would undoubtedly blame Saul for everything. And maybe, the source of a secret kink?

He'd fix that. Saul started injecting his chakra within her and forcibly dispersing the memory. It worked for a time, but the connections to her other memories brought it back. It was a phantom of what it once was, but she would still remember it. He dispersed it again, and it came back again, fainter.

"Hmm... This is more difficult than I thought..."

Instead of dispersing the memory itself, Saul then instead severed all the connections. The memory instantly lost its vibrancy, floating around with little emotions. Then connections suddenly shot out from it to the memories it was once connected to and became strong once more.

"That doesn't work. The most simple way would be to continuously disperse the memory. Since it gets fainter and more phantom-like each time it is dispersed, eventually the memory would not be easily recallable."

He scratched his chin while looking up at it.

"But that would use a lot of chakra. I can't afford to do that as a shadow clone. Plus, I'm afraid some of my chakra might remain inside her for weeks with that solution."

Forced to come up with a more elegant solution, Saul spent a while in Hisame's unconscious mind, thinking. Finally he had an eureka moment.

"What if I get rid of the connections, and then disperse part of the memory. I'll replace that dispersed part with something I create with Genjutsu. The real and the fake should work together to create new connections on their own, and that patchwork memory will serve as a framework!"

Saul erased everything related to his arrival as a refugee, instead replacing it with a dark figure of a deer, galloping through the forest and accidentally stumbling by kicking her in the back of the head. Thank goodness it was dark, and she couldn't really see much. Otherwise, he was afraid the memory of the deer's appearance might raise some questions. Dark as it was, he was able to create a convincing illusion within her memory.

It formed connections, this time to different memories and showed much different emotions. The Genjutsu illusion made from his chakra continuously played alongside her true memory. It was not replaced this time.

Saul sighed. It was done. This method of his had an obvious flaw however, that he'd need more testing to properly assess. The Genjutsu was maintained by his own chakra; he had left enough for a few days. Once his Chakra expired and there was none left, he hoped the continuous Genjutsu of playing that memory would cause her other memories to restore the fake memory based on the formed connections.

He did not know whether or not that would be the case however. Maybe the memory of what happened would disappear, maybe her original memory would come back. He had no way of telling now, but the refugee whose appearance he had taken would be the biggest evidence of success or failure after some time. Speaking of which - he had more work to do. 

The Shadow Clone left Hisame's mind. He then pulled up her panties, pants, and wiped off her own fluids off her body. His would be taken care of by something a little more thorough. Once he finished doing the final touches on her appearance, he dispelled himself. All his traces on her body, whether it be cum, sweat, scent, or saliva disappeared in that instant.

.

At the Fire Duke's Slave Quarters

.

The Saul watching the spared refugees startled. In that moment all the memories of the dispersed clone came to him. They were sleeping at the moment; the poor startled refugees were finally getting some well deserved rest.

His eyes locked upon the shaggy haired refugee, brother of the man who was killed, as he slept. He approached from above, walking along the wall and ending up underneath the man's bed. A glowing green hand reached out from underneath his sheets, grabbing the man while he was sleeping.

It was much simpler than he remembered. With just a thought he was already at the memories of the man's night, being cowed and quartered by the overseer, eating a simple meal, and heading off to rest. The man had sat awake, crying for a while about his brother.

Saul used the same method of Genjutsu he had on him, except this time it was even easier. Unlike with Hisame, he was able to freely manipulate the man's miniscule chakra, forming memories within him as if he had created them himself. It was so easy in fact that Saul worried he had done something wrong.

Regardless, Saul made the man remember he snuck out to find the bound ninja, have his way with her in a rage, and then knocked her out before fleeing back to the Duke's area. Saul infused a strong feeling of needing to keep it a secret, then left the man's mind.

This was his failsafe. If something went wrong with Hisame, this man's memory would be the key towards obscuring his relationship to the situation. He'd believe he did such a thing, so he would act in a way that the real culprit would if confronted.

Double checking the man and finding nothing wrong, this version of Saul also dismissed himself. Time to wait and see.

Author's Note: There are many scenarios of Genjutsu being shown to erase, alter, or read memories and control minds in the original series. It's not really explained anywhere - but I came up with the best explanation I could regarding it that would match certain in-universe scenarios.

Like Anko, who's memories were erased by Orochimaru into believing she had been abandoned by Orochimaru, when in-fact, the opposite was true. She was able to recover her memories by continually visiting the places where her memory was lost - jogging the 'connections' to restore the original memory. Thus, Orochimaru's memory erasure method would be continuous dispersal according to my in-universe logic. Simple but effective.