Under The World(2)

Yamada's Zanpakutō transformed into a red great sword, with a black hilt in the shape of a cross. Before the Zanpakutō could finish releasing, Omega flash stepped in front of her and prepared to cut her down.

He threw a powerful over head slash, but was surprised to see his handless arms instead. His Zanpakutō along with his hands still grabbing on to it, was left behind as they fell to the ground.

He instinctually duct as he felt a light breeze flash over his head, and quickly returned back to the side of his father.

"His Zanpakutō is big, but that's all there is.", Yamada said. But Tachibana thought otherwise.

"Are you sure about that? How about you check again?"

The moment she blinked, his severed arms had been reattached, and his sword was back in his hands. He took another fighting stance, prepared to strike again. However the one who would strike first this time would be Yamada.

Both Omega and Tachibana dodged as a giant invisible slash tore the cement and made its way towards them. While Tachibana stayed behind, Omega advanced towards Yamada once more, before dodging another one of the invisible slashes.

But right as he was only inches away from Yamada, another slash cleaved him right in half, splitting him in two.

Yamada just sighed as she pointed her sword at Tachibana once more.

"This boy isn't all that you hyped him up to be. He was able to read my attacks some what, but that's all."

Tachibana let out a sly smirk, and in response to that, a barrage of slices neatly chopped up Omegas body, until only a pile of flesh was left.

"I knew you were strong, but I didn't know you were this ruthless too."

"Ruthless? I guess that's how others saw me. You on the other hand, are worse than scum!"

She fired another invisible slash from her blade, but oddly it curved around Tachibana before destroying one of the red pillars behind him. This shocked Yamada.

"I've been planning this heist for a long time now. For what I need to do in the future, I need to take my Zanpakutō back. My attack on Seireitei wasn't just random decision, but I needed to draw at least Kurosaki, Kenpachi and Kyōraku's attention away while I came to this place. But you being here was always unavoidable. No matter how I planned, you would always come down here."

"Is that meant to be a compliment?"

She felt a sudden surge of spiritual pressure behind her. She turned around, only to see Omega rising out of his own remains. He was covered in a pool of his own blood, but the amount of killing intent he radiated was considerable.

Another invisible slash travelled towards him, but Omega this time deflected it with a simple slash from his Zanpakutō. 

Once he did, he finally uttered his first words.

"The real battle starts here."

Eventually fully healing, he flash stepped in front of Yamada once more. He had gotten noticeably faster compared to before, but it was still manageable. he swung his sword at Yamada, while she countered with her own.

Allowing the two to clash blades for the first time.

Despite how big omegas Zanpakutō was, he had an easy time swinging with one hand, while Yamada needed two to keep up. They continued to clash swords for while, allowing them to gauge each others strengths and weaknesses. 

Omega could feel the massive experience gap between the two, while Yamada could feel Omega's inexperience which was present in his Zanpakutō. Because of this, Yamada began to overwhelm him with a flurry of slashes.

Yamada was about to preform an overhead slash, and Omega would try to block it, yet there was no collision of blades. That's when he realized it was a feint attack, as another invisible slash, hit him in the torso.

Surprisingly, the slash tore through his Shihakushō, but it only opened up a decent wound across his body. Before Omega could fully react, Yamada pierced her own Sword through his chest, before chanting.

"Hadō #97: Gisei noken!"

Red veins of spiritual pressure travelled through Yamada's sword, as an intense red flame began to burn out of it. Its heat and intensity instantly burned through Omega.

Cutting him in half once again, and also setting his remains on fire.

Yamada backed away, and was surprised to see Omega almost immediately return to his original shape. 

"This boy! He's not just regenerating is he?? Every time I attack him too, I seem to be doing less damage. That Kido spell should've eviscerated him but he still had remains to grow back from. What is it? Adaptation?"

Omega flash stepped towards her with even greater speeds than before, but this time, Yamada could barely keep track of it.

As he swung his Zanpakutō, Yamada leaned backwards, letting the blade fly above her face, just inches away from cutting of her head. The second it passed through, she fired several invisible slashes that continually barraged Omega in the same spot in his chest.

The sheer power blew him back a great distance, but he quickly regained his footing as he shoved his sword into the ground.

The damage to him was minimal. He might as well have gotten a paper cut. Yamada was shocked at how ineffective her Zanpakutō had become. It didn't make sense.

Not that long ago her attacks were easily ripping him in half, but now he could tank them with ease. His growth speed was utterly incomprehensible.

Then finally, Yamada noticed it. Although she hadn't taken any damage this entire fight, the same couldn't be said for Omega.

But despite that, amidst the destruction caused by her attacks, there wasn't a hint of blood at the end of them. Not one ounce had been spilled which belong to Omega.

"Time? No, he's erasing causality. He' s undoing the damage delt by my attacks while also learning from it, and predicting it an advance. And maybe he has a bit of foresight too? Either way, this ability activates even when he dies, so killing him is going to be a pain in the ass."

Yamada's hypothesis was largely accurate. The only detail she had missed out when cracking this ability, was that it only affected him, and not his surroundings or others.

Hence the damage from the attacks still being left on the battle field.

Tachibana had quickly realized that Yamada figured it out. And congratulated her for this.

"You really are the grandmaster of Shino Academy. I'm glad that Omega's first opponent was someone like you."

First?! It would explain his initial inexperience. But now that gave Yamada another reason she could not lose. It wasn't just Soul Society, but her dignity that was now one the line. Her opponent was functionally immortal, and if she held back any longer, he would eventually catch up to her and at that point she would inevitably lose. There was only one course of action now that she could take.

"BANKAI!"