TG: Starting with Mangekyo

Byakuya could tell that Eto was asking about his Mangekyo Sharingan, which resembled a kakugan, and the Susano'o, which looked strikingly similar to a kakuja transformation.

He promptly explained, "It's true that I'm a half-human, but I don't have a kakuhou. You can think of it as my eyes undergoing a mutation"

Aside from the absolute secret of the Kamui, which he couldn't reveal under any circumstances, Byakuya was fairly transparent with Eto about everything else.

The Kamui, like his identity as a transmigrator, was something he could never let anyone know.

"I don't believe it. Without a kakuhou, there's no way you can release kagune. What you just did was clearly a kakuja transformation" Eto said, convinced the lolicon bastard was trying to fool her.

Indeed, in the world of Tokyo Ghoul, it's basic common sense that only a kakuhou can release kagune.

But Byakuya had unintentionally broken this rule.

Even he was surprised by the Susano'o, which bore a striking resemblance to a kakuja transformation. He hadn't expected his Susano'o to mutate due to the influence of RC cells. Simply put, his Susano'o was formed by kagune, as RC cells solidify.

However, since he didn't have a kakuhou...

This phenomenon could only be explained as a mutation caused by the fusion of the Mangekyō Sharingan with RC cells.

"Let me show you my eyes first"

With a thought, Byakuya activated his Mangekyo Sharingan. "See? Doesn't it look completely different from a normal ghoul's kakugan?"

Eto leaned closer for a better look and confirmed that his eyes were indeed very different from her kakugan.

Although both were blood-red, the patterns were entirely distinct.

"What exactly is this..." Eto murmured, utterly baffled.

This was the first time she'd encountered such a mutated half-human.

"And as I said, I don't have a kakuhou, nor can I freely release kagune. If you don't believe me, take a look" Byakuya offered, removing his shirt to reveal his back to Eto.

There are four types of kakuhou, and their locations vary, but they are always found on the back.

While it wasn't immediately visible, Eto's strength and experience were sufficient to sense, through her kakugan and close proximity, that Byakuya truly lacked a kakuhou.

"There really isn't one..."

Despite her disbelief, Eto couldn't deny the evidence before her eyes.

"That's why I said I'm a mutated half-human. If anything, you could say I'm somewhere between a half-human and a half-ghoul" Byakuya explained. "Perhaps you're unaware, but the Washuu Clan has long been conducting experiments on combining humans and ghouls."

"I know about that. Half-humans like you are the result of those experiments..." Eto began, only to be interrupted.

Before she could finish, Byakuya interrupted, "I'm not talking about that. I mean surgical experiments to directly turn humans into ghouls"

In the original timeline, a company called Sphinx was run by Kurona and Nashiro's father, Nanao Yasuhisa. The company appeared to supply CCG with RC fluid, an essential material for Quinques and RC suppressants.

However, hidden in its underground laboratory, Nanao collaborated with the CCG to conduct experiments on turning humans into ghouls. This secret was known only to members of the Washuu Clan within the CCG.

In the original timeline, Eto was aware of these experiments, but evidently, she hadn't learned of them in this timeline.

"Turning humans into ghouls... They really go to any lengths to create half-ghouls" Eto sighed.

She had only known of the Washuu Clan's attempts to create half-ghouls through interbreeding humans with ghouls. The half-humans of the Sunlit Garden were the result of these experiments. She had no idea the Washuu were also conducting secret surgical experiments.

"Exactly. The Washuu Clan's ultimate wish is to become human, and half-ghouls represent the ideal result of that wish" Byakuya said.

Half-ghouls like Eto, with immense strength and the ability to blend perfectly into human society, were the Washuu Clan's crowning achievement.

As for artificially created half-ghouls like Kaneki, those were incomplete experiments carried out in secret by Akihiro Kanou. By the time of the original story, the Washuu Clan had already abandoned such experiments, and Nanao had been silenced for his efforts.

Eto chuckled coldly. "Makes sense. If they could become human, the Washuu would have even more freedom to control the world."

The greatest fear of the Washuu Clan was their true nature as ghouls being exposed, which would undermine their dominion over society.

"Anyway, I believe you now. In some ways, you're even more unique than me. A half-human who can use kakuja-like abilities without a kakuhou... The Washuu Clan once produced a natural-born half-ghoul, but what you are is unheard of."

Finally convinced, Eto added, "By the way, you're aware of the Washuu Clan's greatest taboo, aren't you?"

"Yes" Byakuya replied. "The Underground King, or the original One-Eyed King."

Byakuya was only the first One-Eyed King of Aogiri Tree. The original One-Eyed King, in the true sense, was a naturally-born half-ghoul from the Washuu Clan many years ago.

However, that half-ghoul despised the Washuu Clan despite being one of their own. He opposed the clan and even underwent 'dragonification'.

Ultimately, this individual was banished to the underground depths of the 24th ward, where they were known as both the One-Eyed King and the Underground King.

"The remains of that dragonified form are still deep within the 24th ward. Come to think of it, if you could also dragonify, you might have a real chance at overthrowing the Washuu Clan" Eto mused.

"You do have Washuu blood, don't you? Theoretically, you could transform into a dragon" she added.

The Washuu Clan's long history of cannibalism had strengthened their bloodline to the point where modern Washuu members were born as natural kakujas.

This also made it possible for those with Washuu blood to dragonify, transforming into massive, city-spanning creatures.

"Yeah, I'd rather not..." Byakuya muttered, feeling speechless.

Instead of becoming a dragon, he'd prefer to use his Perfect Susano'o to destroy anything in his way. At least that way, he could return to being human whenever he wanted.

Eto had only been joking and quickly dismissed the idea.

"True. I wouldn't want you to turn into that kind of monster either. What if you couldn't return to normal..."