The sword isn’t bad, is it?

"Sure enough! If the Shinigami is strong, the Zanpakutō is strong."

"A Zanpakutō of the illusion system can only be pushed to the ultimate level in the hands of a king."

"In the final analysis, Kōga's capabilities as a Shinigami are limited, and he could only create Muramasa as the second-best within the illusion-type Zanpakutō. But in Aizen's hands, after rewriting the soul essence, Muramasa immediately evolved on its original foundation—not only did the release command change, but even the Shikai name became different."

"The same goes for Kyōka Suigetsu. After incorporating the power of the newly reborn demon sword Muramasa, it too underwent enhancement. Although the Shikai name remains unchanged, the release command has been altered."

Tōsen Kaname didn't know that Suzumushi had changed, but Aiyan had secretly entered the spiritual world, glanced at Hypnosis-bound Suzumushi, and helped it change its master.

This couldn't help but make him sigh.

In the world of Shinigami, it truly does revolve around hybrids.

Whether it's Zanpakutō or Shinigami, the more mixed they are, the more powerful and limitless their potential becomes.

Just like Ichigo, who clearly had only one parent, but possesses Hollow, Quincy, Shinigami, and Fullbring traits.

Each ability is stacked with various bloodlines.

And here—Aizen merely fused Kyōka Suigetsu with the demon blade Muramasa, not even incorporating powers beyond Shinigami—and his strength immediately skyrocketed.

Not only did he gain dual swords of illusion-type, but their abilities also significantly increased. After Shikai, even his Reiatsu became far stronger than before.

"Alright, it's time for you to come out."

"You might feel a little wronged."

"Endure it a bit, okay?"

After lightly testing Suzumushi's Hypnosis, Aizen smiled gently and asked in a tone that sounded polite but brooked no refusal.

"Yes, Lord Aizen."

"I don't feel wronged. On the contrary, I've been looking forward to it."

"Because, it is my honor to personally take part in purging the source of Soul Society's corruption."

Upon hearing this, Tōsen Kaname immediately knelt, his voice full of reverent excitement.

At this moment,

He was completely immersed in the joy of avenging his fallen friends and gradually dismantling the noble houses and system of Soul Society step by step. He had no idea that his Zanpakutō, Suzumushi, had already fallen under Aizen's Hypnosis and become a toy in the hands of the master he loyally served. Let alone realize that Suzumushi, once loyal to him, had already changed allegiance and could become the very weapon to end his life at any moment.

Puff.

When Aizen heard this, the smile at the corner of his mouth grew wider.

He reached out and gently pressed Tōsen Kaname's forehead, and spiritual pressure rippled out like a pulse.

Pata.

Tōsen Kaname only felt his consciousness grow rapidly drowsy, and the next moment he collapsed softly at Aiyan's feet.

"Brother, your Kōfūin is also a soul-slaughtering dual sword!"

After knocking Tōsen Kaname unconscious with a casual gesture, Aizen asked suddenly, though his tone was already full of certainty.

"Yes."

"She has both light and dark aspects, though she usually prefers to act as one."

"So, she can be a Zanpakutō where light and darkness are integrated—or a Zanpakutō where light and darkness are separated."

Since Aizen had seen through it, Aiyan no longer concealed it. He unsheathed his Zanpakutō in front of him, without announcing the Shikai name or release command, and the blade separated on its own into two swords.

One was golden throughout, shaped like a blade of light, exuding boundless sharpness. Even a slight tremor would slice the air around it, making one instinctively fearful.

The other was pitch black, like a blade of darkness, exuding terrifying gravitational force. It simply floated in the air, yet any light passing near it would be drawn in and unable to escape.

"Light and darkness as one, the dual swords of light and shadow—and this is only the Shikai form. What astonishing power."

"Brother, this is why you went to so much trouble to capture Muramasa and give him to me!"

"You even considered that I might reject him because of my nature, so you gave him to me as a birthday gift."

Aizen glanced at Kōfūin, first praising them, then shifting the subject:

"You hold two swords—each the strongest in the light and dark categories—while I only wield Kyōka Suigetsu of the illusion system."

"Jealous? No. My ambition isn't limited to such things, and more importantly, there's no little brother in me who feels jealousy or resentment."

"So, to spare my pride, you didn't need to hide your strength on purpose—or go so far as to use such a roundabout method to hand me Muramasa."

He looked into Aiyan's eyes.

"You're overthinking it."

"An elder brother simply gave his younger brother a birthday gift—no need to add layers to it."

"By the way, the sword isn't bad, is it?"

Aiyan's gaze rippled slightly upon hearing this, but quickly returned to calm.

When he had first crossed into this world, he hadn't yet discovered the ability to cultivate independently—or rather, he hadn't even grasped Zanpakutō, Reiatsu, Zanjutsu, Shunpo, Hakuda, or Kidō, and thus had no capacity for self-cultivation.

In the chaotic District 80, he and Aizen could only rely on each other to survive.

It was precisely because of that shared struggle at the edge of death that he understood: while Aizen presented himself as elegant, kind, and courteous—he was, in fact, cold, ruthless, and fiercely ambitious. And yet, Aiyan still chose to treat him as a younger brother.

After all, he himself was a transmigrator with no real sense of belonging to the Soul Society, Seireitei, Shinigami, Quincy—or even this world.

Whether replacing the Soul King or overturning Seireitei, even if Aizen sought to plunge the Three Realms into chaos—he didn't care.

"Not bad."

"After accepting the essence of my soul, Muramasa's release command and Shikai name both changed, and his Zanpakutō also evolved."

"It's a good thing."

Aizen nodded, affirming the transformation of the demon sword Muramasa, and also acknowledging Aiyan's power.

"Something bad?"

Aiyan caught the subtle implication in Aizen's tone.

"The bad part is—it's easy to become dependent on that power."

"Whether it's Kyōka Suigetsu or Muramasa, they are both of one soul. Once evolved through Shikai and Bankai, it's far too easy to become their subordinate."

"Just like Kōga—without Muramasa, he's nothing."

Aizen didn't hide his thoughts and openly explained that he disliked being dependent on Zanpakutō.

"Aizen, your thinking is a bit extreme."

"A Zanpakutō is a product of your soul's essence. It's an extension of your soul—just as your limbs are extensions of your body. Would you cut off your own arms or legs?"

"As for saying you won't rely on Zanpakutō—that's admirable. A Shinigami shouldn't depend on Zanpakutō alone. Reiatsu, Kidō, Zanjutsu, Hakuda, and Shunpo—none should be neglected."

"Just like the heart, liver, spleen, lungs, kidneys, and brain—they are all indispensable."

Aiyan understood it all too well.

No wonder Aizen, despite having Kyōka Suigetsu, rarely used it—especially after obtaining the Hōgyoku. Each time he grew stronger in soul and power, he used Kyōka Suigetsu less and less.

At first, it was to put himself in danger and force the Hōgyoku to assist his evolution, but later on—even Kyōka Suigetsu was shattered by his bare hand.

It turned out that Aizen had such tendencies even back then.

Now, Aiyan was slightly puzzled.

Why do Shinigami with illusion-based Zanpakutō seem to have such unique habits?

They seem to enjoy breaking their own Zanpakutō for no reason.

Kuchiki Kōga was like this—the first thing after being freed was to cut off Muramasa.

Same with Aizen Sōsuke—after his evolution, the first thing he did was destroy Kyōka Suigetsu.