Yoruichi’s Bankai

The moment Yoruichi released her Bankai, her black hair had turned white, and her Reiatsu-Ki had increased more than 20 fold, creating a pressure around her that was strong enough to push the giant down even further.

The Surtr hurriedly raised its greatsword in defense, but it didn't really do anything. However, detecting Yoruichi's Reiatsu-Ki, the Dungeon 'cried' and started funneling more Magic Power towards the Surtr, initiating its mutation.

On Yoruichi's side, after her hair, it was her kodachi's turn to become pure white. Different from most Bankai, Yoruichi's has a rare one that doesn't change in shape, however, only its shape had remained as she gritted her teeth just holding it.

"Kyo no Kougou, Byakko (Void Empress, Byakko)!" As she announced the true name of her Bankai, she immediately felt the change as the weight of her blade became several thousand tonnes. Using all of her strength, Yoruichi aimed at the left horn that was behind the greatsword and swung her blade towards it, "HAAAAHHH!!!!!"

Compared to her normal moves, Yoruichi's swing was agonizingly slow. However, although its weight was enough that Yoruichi could feel the gravity generated by it, the deadliest thing about it was actually its ability to tear space itself.

Following the trajectory of her swing, the Surtr wasn't able to react when its left horn and left arm left its body, along with the greatsword that was suddenly split in half. The wall of the Dungeon was also cut deeply, but fortunately, it isn't enough to summon the Juggernaut.

The Surtr roared in pain as the excess Magic Power that was being injected into it spilled from its severed limb.

Yoruichi planned to let go of her Zanpakuto and recall it in its basic state, however, she was shocked to know that her hand was stuck on the hilt of her Zanpakuto, 'What!? Damn it!'

As a result, Yoruichi spun uncontrollably, leaving her at the mercy of her own blade as she tried to seal back her Bankai.

Kuroka saw this and called out to her, "Yoruichi!?"

However, she couldn't actually come to her side as the Surtr started acting up and was about to smash Yoruichi with its right arm. Without any choice, Kuroka attacked it with her Sacred Gear and Black Flames, catching its attention, albeit, only slightly.

Yoruichi, on the other hand, tried her best to take back her Bankai, but she wasn't able to do so until her hand hit the ground, crushing her fingers under the weight of the pure white kodachi.

Without groaning in pain Yoruichi immediately dematerialized her Zanpakuto after deactivating her Bankai and hurriedly took out a potion created by Kisuke, directly pouring it on her crushed hand. She then took another bottle and poured it on her arm which was ruptured due to the stress of the single swing, 'I thought I was strong enough... I didn't think Byakko would get even heavier.'

When she was just a Lieutenant within Soul Society, her Shikai was actually blades that were attached to her arms like claws. She, however, was not very fond of it as they were thrice her size. Although they were extremely sharp, it didn't suit her desired combat style which prioritized speed.

Not just her, but everyone who understood enough thought that her condition was an anomaly as the Zanpakuto should have adapted to the Shinigami's fighting style, and never the other way around.

This phenomenon immediately captured the attention of Oetsu Nimaiya, the creator of Zanpakuto, and asked The Shihouin Clan to let him inspect Yoruichi's Zanpakuto. Although many were curious about the result, Nimaiya only revealed it to the then head of the Shihouin Clan and Yoruichi herself, that before the soul of her Zanpakuto was formed, something else had replaced it.

From that time, Yoruichi could only remember that Nimaiya can't actually give her a new Asauchi as her Zanpakuto was already bound to her.

From then on, Yoruichi worked hard on her Hakuda that could match her Shikai and at some point, she learned to enjoy the style. However, when she achieved her Bankai, another slew of problems came up.

First, she was not strong enough to wield her Bankai despite it returning to a much smaller form. Second, Byakko wouldn't allow her to use her Shikai anymore. And finally, the third, she's forbidden to use her Bankai due to its innate ability to disrupt the surrounding space and could potentially destroy the space dividing the realms.

As such, when she became a Captain, she stopped carrying her Zanpakuto. Practicing Hakuda from the start was her only silver lining.

Even then, Yoruichi actually never gave up on her Zanpakuto. Aside from prioritizing speed, she also started working on her strength to at least carry her Bankai. Due to that, she was known as the Flash Goddess due to her speedy, but violent style of combat.

'Kisuke said that there should be a way to control its weight and I also believe the same... But Byakko won't even listen to me... Am I still not worthy?' Yoruichi asked herself.

All of a sudden, she heard a low snort from her 'lovely' cat and was stunned for a short moment. Somehow, she could feel Byakko's frustration emanating so instead of being discouraged Yoruichi felt motivated, 'I see... Then I just have to use you over and over again to make it up to you for when I neglected you.'

Yoruichi finally realized her mistake. Although she never gave up on Byakko, she also didn't communicate with her that much, thinking that she can only properly make use of Byakko once she fully mastered her Bankai.

At the next instant, a warm flow of Reiatsu-Ki suddenly emerged from Byakko and silently connected to her soul. Yoruichi's eyes widened at this but she didn't know that all of those who achieved Bankai were already used to this feeling, 'What's this?'

Although she didn't receive an answer, she had a feeling about what it was and turned her attention towards Surtr who's flames had become hotter and turned blue. Yoruichi then turned to Kuroka, who was currently holding it back and shouted, "Kuroka! I'm ready!"

Kuroka gathered her Black Flames and blasted the mutated Surtr with it, pushing it until the walls, shaking the Dungeon from the impact, "Make it fast. People are already rushing towards here, nyaa!"

Yoruichi nodded and eyed the Surtr that was currently recovering its balance. Using Flash Step, Yoruichi reappeared a few meters away from its head. The Surtr, noticing her presence again, didn't think about defending but immediately gathered flames to its throat.

Yoruichi then closed her eyes and concentrated, feeling the warm stream of Reiatsu-Ki from Byakko. Opening her eyes, her hair turned white again along with her kodachi, "Bankai! Kyo no Kougou, Byakko!"

At the same time, the Surtr released the blue flames that it had gathered and launched them towards Yoruichi. However, unlike before, Yoruichi easily pulled out her kodachi and was able to swing it with speed incomparable from the first one.

Although the overall weight of the kodachi was reduced to several hundred tonnes and the destructiveness behind it was also greatly reduced, its effects on space hadn't changed. From its remaining horn until its leg, the Surtr was set asunder along with its blue ball of flame.

The Surtr wasn't even able to cry when it was reduced to ashes and its Magic Stone that was split into two dropped on the floor.