"What will we be learning today?" asked Takuma as he took his genjutsu notebook from his backpack.

It had been two weeks since Takuma's first lesson with Mikoto at her home, and in just that short time, Takuma felt like he had learned more about genjutsu than he had known before. That knowledge in no way helped him create genjutsu or improve his ability to cast genjutsu he knew, but by no means was that knowledge useless. He could feel how the building blocks Mikoto was imparting him would one day be of tremendous use as he explored the world of genjutsu.

"Have you ever asked yourself why people don't question themselves in the face of the impossible?" asked Mikoto. A plate of light refreshments sat between them as usual.

"What might you mean?" Takuma returned.

"There are genjutsu which can be created through realistic practical means, but most genjutsu often lie in the category which can't be created or are near impossible to exist. So, my question to you is, why do we believe the truly bizarre we are made to experience while under the influence of a genjutsu?" Mikoto continued, "Why can a person see their long-dead loved one appear in front of them and wholeheartedly believe it to be true— and experience the full force of emotions without doubting that the sight in front of them is false?"

Takuma was left speechless in the face of Mikoto's question. He had no answer for it; he didn't even have a guess. In fact, Takuma had never questioned how genjutsu worked. Before he learned Genjutsu: Mist Servant Jutsu, the question was never in his orbit, and after he learned it, he simply accepted a genjutsu working as a fact. He was sure there was no explanation in any of the five genjutsu scrolls he currently possessed.

Takuma wondered why he had never questioned it. Was it because ever since Yuhi Kame had trapped him in a genjutsu which brought out genuine fear in him until he naturally slipped out that he accepted it as a universal truth?

"I didn't know, ma'am." Takuma's curiosity peaked, and he hung onto the next words Mikoto spoke.

"Until three decades ago, we didn't have the answer as to how genjutsu actually worked. The creation of jutsu, be it ninjutsu or genjutsu, was such a long time ago that much of the knowledge had been lost through the passage of time. We knew that certain series of hand seals and molding chakra in peculiar ways would create genjutsu, and the knowledge of creating different effects was more than plenty— but we didn't know how genjutsu actually interacted with the brain and mind to cause the intended results."

Takuma nodded. Chakra and jutsu weren't completely understood fields. Just like any scientific field, they too were studied every day by specialists and academics who devoted their lives to understanding the mystic force which made the impossible possible. It could be said that the study of chakra was still in its infancy, used only as a weapon because the researchers were shinobi, and the topics of research were funded by shinobi, making the research topics very biased towards militaristic uses. The only field with applications beyond warfare was iryo-jutsu which anyone could enjoy.

Takuma was sure one day, the secrets of chakra would be unlocked to a level where it would leak into normal lives. As for when that time would come, he didn't know— if the nature of this world didn't change, perhaps he wouldn't see it in his lifetime. The thought made him feel sorry for the world.

Mikoto continued, "However, four decades ago, we developed the technology which allowed us to inspect the brain." It was the invention of the MRI. "One of the experiments conducted in those early days was to study how the brain reacted under the influence of genjutsu…."

"Oh!" Takuma felt excited learning about knowing such a piece of history.

"…. the study resulted in us learning nothing."

"Oh…"

"It was a decade after the initial study that one of the researchers noticed how the scans of the brain of someone under genjutsu looked similar to those of people suffering from mental diseases like schizophrenia," Mikoto smiled. "We simply didn't have enough data when the initial study was conducted, but after a decade of studying all types of people, enough was recorded that previously asked unanswered questions gained answers."

Takuma released a breath he didn't know he was holding and subconsciously sat up straighter. He was not a naturally curious person who asked questions, but learning new and interesting things was always a welcoming experience.

But then he focused on Mikoto's words and realized what she had just revealed.

"I-Is there a chance of developing a mental condition because of genjutsu," Takuma asked with trepidation. Neither did he want to get a mental disease, nor did he want to subject anyone to one.

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Mikoto laughed as she hid her mouth behind her hand. She laughed for a good few seconds before calming down. "You don't have to worry about that. A few studies have been done, and a correlation hasn't been found yet."

Takuma breathed a sigh of relief.

"To put it crudely, genjutsu alters the brain's functionality to something similar to mental diseases, but unlike mental diseases, the user has much more control and freedom. The brain is so disrupted that it loses touch with reality and begins accepting everything you throw at it, just like how an unstable mind accepts hallucinations as reality."

Mikoto took a pause and picked up her teacup. Knowing she had stopped for him, Takuma wrote everything he had not yet.

"What about when the target realizes they're in a genjutsu?" asked Takuma.

He had talked to Nenro and others about how they felt at the point of realization, but unlike his experience of complete, instant detachment, their testimonials were different; according to them, they were still very much under the thrall of the genjutsu, and it took the effort to muster the intention to break the genjutsu. Nenro had specifically pointed out that the amount of effort required to break away depended upon the user's skill level and that if someone was skilled, they could potentially pull the target back into complete thrall after they realized they were under a genjutsu.

"Brain and chakra are complex things beyond human understanding. The brain will try to correct itself, and if gaining control over another's chakra was so easy, genjutsu would be everyone's weapon of choice," said Mikoto. "There are internal and external factors out of your control, which can all lead to the target breaking free. The only way to reliably retain control is to have a strong one from the get-go."

Takuma scratched his head with the pencil. "Then what are the main criteria for a strong genjutsu— its ability to maintain control over the target or affect the target the most? What's considered the strongest genjutsu?"

Mikoto put her teacup down. "You're still looking at genjutsu as if it's ninjutsu. It is not. I have told you this before. While judging a genjutsu, you don't judge the jutsu but the shinobi behind it. Let's take your Mist Servant Jutsu as an example; can you change the connection component from visual to auditory?"

Takuma, of course, couldn't.

"A true user could make that happen. A genjutsu is just a build-it-yourself jutsu that can be adapted according to the requirements of the moment. Why put in the effort and chakra to create a long-lasting connection when you only need the genjutsu to last for a few seconds— similarly, why cast a 'strong' torturing genjutsu when you only wish to detain the target and don't wish to harm them? It's all about managing effort and chakra."

"How long would it take me to become a true genjutsu user, as you put it?" asked Takuma.

"That depends entirely upon you. The faster you learn, the faster you'll be able to achieve the goal," Mikoto shrugged. "As to answer your previous question. The strongest genjutsu— as I said, I'll look at the person behind it. What's the quality of the strongest genjutsu shinobi? It's personal preference, and others will give you different answers, but the strongest user would be the one to hold a target in a genjutsu even after informing the target they were in a genjutsu."

Takuma was baffled. How could that be possible? Any person who knew they were in the genjutsu would immediately break it. "Has there ever been any such shinobi?" he asked.

"The Second Mizukage, Hōzuki Gengetsu," said Mikoto with an undertone of respect. "It was said that with the help of his summon, a giant clam, he could cast a genjutsu so strong that even after informing his targets they were in a genjutsu, they would be helpless to break out of it. He could play with a hundred shinobi simultaneously without breaking a sweat."

If it was true, then Takuma could see the Second Mizukage as the contender for the strongest genjutsu user, but he knew two people who he thought held a stronger claim as the strongest genjutsu users. Both were from the same clan as his teacher in front of him, and one was her son.

Uchiha Itachi and Uchiha Shisui. The former with his Tsukuyomi and the latter with his genjutsu, of which he couldn't recall the name, only that it was 'Inception' on steroids.

Takuma glanced at Mikoto's onyx eyes. Those eyes were absurdly strong weapons, but what was scarier was that they could become even stronger. So strong that they had made Itachi and Shisui contenders to possessors of the strongest genjutsu. But the most terrifying part was that with the right extremely rare circumstances, the eyes could become even stronger.

He shook his head. It was useless thinking about those two monsters. He didn't know when Shisui gained his Mangekyo Sharingan and if he had it now. As for Itachi, as Shisui was still alive, he didn't have access to his Mangekyo Sharingan.

"A question to you, Takuma. What, according to you, would be considered the strongest genjutsu?" asked Mikoto.

Takuma contemplated the question for a moment. "My answer might change if I give it more thought. But at this moment, a genjutsu that the target wouldn't want to leave is the strongest genjutsu," he said.

"… A genjutsu the target won't want to leave?" Mikoto looked stunned.

"Life can be tough, ma'am. For many, it's miserable. What if a genjutsu gives you everything you desire— a happy life with zero problems? I would bet everything I own that you would find plenty of people who wouldn't want to get out of something like that."

He looked outside. Due to the time of day and the building structure, he couldn't see the sun shining. But he could imagine a moon— a full blood red moon with nine black tomoe on its surface.

"A genjutsu that gives people the life of their dreams."

Takuma closed his eyes, and the faces of his family flashed before his eyes. He wondered if, in ten or twenty or thirty years from now, he could remember their faces, voices, the memories with them… the thought scared him to the core.

If given the choice… he didn't know if he would be able to refuse.

He didn't think his resolve was that strong.

He didn't think his resolve would ever get that strong.