Fourth Release- Memories

"Here it is."

Running down into the depths of Seireitei, the Captains, Lieutenants, and the Royal Guard during Isshin's time as a Royal Guardsman reach an abandoned room hidden under Soul Society. Walking towards an ominous looking coffin, a slightly younger Captain Yamamoto grips the handle of this Zanpakutō, Ryūjin Jakka.

"Yamamoto. Be wary."

"…Yes."

"…If we catch it unprepared, we could exorcise it for good!"

"…Ah, Isshin…"

"…O-Okay."

Isshin Kurosaki, a member of the Royal Guard, slowly unsheathes Engetsu, his Zanpakutō. Isshin is a tall man with spiky black hair and brown eyes. He has thin facial hair around his mouth and on his cheeks. He wears the standard Shinigami shihakusho, along with a tattered Captain's haori, worn like a sash and fastened over his left shoulder. Engetsu has a red handle and hexagonal hand-guard. It is carried from a string wrapped around his belt in an iaidō style, and worn with the edge down like a tachi instead of the edge up like a katana. The end of the hilt has a blue tassel. Several of the other Captains and Lieutenants begin to approach the coffin. A powerful reiatsu emanates from the coffin, radiating white light.

Ka-chink.

With that noise, the lid of the coffin slid open. Rising from the structure, a figure emerges. Bearing ominous blue within magenta eyes with slitted pupils, the rest of this being's figure is shadowed.

"There it is!"

"Watch yourselves!"

"Hmmhmhmhmhm…"

This figure's lips curled upwards, forcing a toothy menacing grin.

"Hello, you bastards…"

White reiatsu permeating from this figure's body, it lets out a bone-chilling cackle.

Whoosh.

In a flash of white light, the figure leaped forward and decapitated the Lieutenant of the 3rd Division with its arm. Spinning around, it kicks an enormous hole through the 3rd Division's Captain's chest. Releasing its reishi through its foot, it vaporizes the Captain effortlessly.

"BASTARD!!"

Rushing forward, Kyosuke Kurosaki, Isshin's cousin, summons his Zanpakutō, Hanegetsu. A large katana at first, immediately activating Shikai, it transforms into an oversized elegant cleaver rather than a formal "katana". He has no tsuba and no proper hilt; what Kyosuke holds is the cloth-wrapped tang. The sword has a golden blade with a silver edge.

"Getsuga Tenshō!!"

At that instant, Kyosuke launched an black crescent moon formed from reishi at the creature, only for it to grab it and crush it with ease. Lunging at Kyosuke, the creature tears him in half in an instant and shatters Hanegetsu.

"Cousin!"

About to run at the creature, Isshin is only held back by Retsu Unohana.

"Isshin. Clear your mind."

"D-Dammit! That thing needs to die right here, right NOW!"

"If you rush forward now, your effort will be senseless."

"…I'll be the one to destroy you!"

With Isshin quickly backing away, the creature grabs the shattered Hanegetsu.

"D-Damn…!"

"Already…?! What the hell is this thing!?"

Yamamoto expresses his disbelief. In only a few seconds, this creature had killed three of Soul Society's strongest fighters.

"Yatte yaruze, Kakusei."

In a flash of light, the broken Hanegetsu began to glow in white light, the same color of the creature's reiatsu.

"WHAT'S HAPPENING!?"

At that moment, the shattered blade of the Zanpakutō became surrounded in white light before shooting forward, restoring the blade to its original form, a new Hanegetsu, only twisted and distorted by this creature's reishi patterns.

"It absorbed Hanegetsu and took control of it…!?"

"Anki. By forcing the spirit of that creature's Zanpakutō into Hanegetsu, it can take control of it and use it as a medium for its own Zanpakutō, retaining the host sword's abilities. Now, Kyosuke's Hanegetsu is that creature's Zanpakutō."

"Shippūga."

Unleashing a spinning running slash, the creature rends several more Captains and Lieutenants into pieces, before grabbing one of the corpses and throwing it at Yamamoto, knocking him off his feet.

"G-Guh…!"

"YAMAMOTO!!"

Now dashing at the creature, Isshin slashes wildly, to which the creature effortlessly blocks with Hanegetsu. Attempting to apply pressure onto Hangetsu with Engetsu, Isshin tries to knock the creature down. However, the creature is unaffected, and merely utters the words,

"Getsuga Tenshō."

Isshin responds with,

"GETSUGA TENSHŌ!!"

Suddenly, the two forces collided. While the creature's Getsuga knocked Isshin through several walls, the creature itself was unaffected by Isshin's own. Almost undefeatable, the creature turned to Retsu and Yamamoto.

"SHIKAI! RYŪJIN JAKKA!!"

As Yamamoto's blade transformed, he leapt at the creature.

"DIE!!"

Smack.

Striking the middle-aged Yamamoto with a swift, clean slash, the creature quickly spun around and struck Yamamoto with a back kick, sending him crashing through several walls.

"Yamamoto!"

Grasping Minazuki, Retsu Unohana began to release her Bankai.

"BAN-KAI—"

"Enough, Retsu."

Emerging from the rubble, Isshin Kurosaki stood, full of resolve.

"Isshin…"

"It's no use just to fight. It's no use just to live. I want to win. I'M GOING TO WIN!"

Grasping Engetsu, Isshin uttered the words,

"Ban-kai. Tensa Engetsu."

At that moment, Engetsu changed. In this form, Engetsu is a daito (Japanese long sword) with a crimson blade. The cross-guard has four prongs bent out to form the shape of the manji (which is the kanji for "ban," meaning "full", as in "full release"). Instead of the cloth the regular Engetsu, Hanegetsu, and Zangetsu have, a short length of chain with a broken link at the end dangles from the base of Engetsu's hilt. Rising up to face this horrifically powerful creature, Isshin Kurosaki focused his gaze on it.

"Ban-kai."

Grasping the hilt of Hanegetsu, the creature spoke,

"Tensa Hanegetsu."

In this form, Hanegetsu is a daito (Japanese long sword) with a golden blade. The cross-guard has four prongs bent out to form the shape of the manji (which is the kanji for "ban," meaning "full", as in "full release"). Instead of the cloth the regular Engetsu, Hanegetsu, and Zangetsu have, a short length of chain with a broken link at the end dangles from the base of Hanegetsu's hilt.

"YAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAH!!"

Rushing at each other, the Captain of the Royal Guard and the creature traded fierce blows that tore a hole in the roof and almost split the sky of the spirit world in half. As their reiatsu flared up to their fullest, Isshin and the creature struck each other with their Zanpakutō with incredible force. As Tensa Engetsu and Tensa Hangetsu clashed, sparks generated from the blades, with neither being backing down.

"Getsuga Tenshō!!"

Releasing the Getsuga from their blades, Isshin and the creature leap back.

"Getsuga Yari!!"

Unleashing and shooting several lances with the tip in the shape of a crescent moon at each other, the two then rush at each other once again. Focusing the Getsuga on their blades, the two clash with even more force.

"You know monster…You've taken too many lives already."

The creature's answer was silence.

"I won't let that go without punishment."

Isshin spoke these words in a fierce tone.

"It's either you or me. Get ready."

Permeating with black reiatsu, Isshin began to change. Isshin's hair turns black, and becomes waist-length. Gray bandages form around his body, tightly wrapped around his torso, right arm, and face, ending just beneath his eyes. The remains of a tattered black cloak cover his lower body. In this form, Isshin's body constantly emits black reiatsu, most of which is focused around his right arm.

"I am Getsuga itself."

Following its opponent, the creature does the same without hesitation. Now facing each other down as the Getsuga, Isshin and the creature begin their final attack.

"MUGETSU!!"

As their voices synchronized, Isshin and the creature seemingly generate a blade of black energy out of thin air, and they grab it. Doing so unleashed two massive veils of black reiatsu that covered the surrounding area and turned the sky black, inflicting immense damage upon each other. The energy then receded, dissipating into the sky. After this final attack, Isshin ran up to the creature and unleashed a memory and power-deprivation Kidō that made it a blank slate.

"ISSHIN!!"

Running over to Kurosaki, Retsu attempts to help him stand.

"Unghh…"

Tossing and turning, Gai Nagareboshi woke up.

"W-What…what the hell was that? I've never had that dream before…"

"Gai, are you okay?"

Hikari, half-asleep, wandered over to where Gai was, curious.

"Y-Yeah…"

"What were you dreaming about?"

"N-Nothing. It's nothing."

"…Are you sure?"

"Y-Yes. Now go back to sleep and leave me alone."

"Aww…"

After hearing this, Hikari left. Staring at the ceiling, Gai sighs.

"What was that? It felt…kinda familiar."

Looking at the time, Nagareboshi then closed his eyes.

"Ah, no matter."

With that, Gai fell asleep once again.