Benihime was still active even when Kisuke fell down, however, that doesn't mean anything if Kisuke doesn't understand what's going on and that's exactly the situation he's in now.
Even then, Kisuke tried figuring out what was wrong by dissecting himself by controlling the blades attached to the red string, only to get nothing out of it. It was on a different level compared to earlier where he just simply doesn't notice the changes in his body. This time, there were really no changes similar to Ichibei's ink but the effect was still very apparent.
'I was naive not completely disabling Kirio-san... Dammit. I've really become soft in strange places.' While he was complaining in his head, he's not really regretting his decision. While it was easy for him to take out Kirio earlier, he doesn't have a way of knocking her out without endangering her life due to how her 'vitality' works.
Kisuke was confident that Kirio would be able to take a beating so he didn't really hold back but finishing her off was out of the question. He couldn't lay a hand on someone who acted like a mother to him when he was just an orphan even for a short time. Not to mention, Kisuke doesn't really see her as an enemy since she's just fulfilling the duty she swore on.
Kirio saw his struggle but unlike Kisuke, she can still speak, "Don't bother. You won't find anything wrong because there's nothing wrong."
Kisuke's eyes turned to Kirio but that's all he could do.
"There's nothing wrong with it because I just reversed the law of life and death." Kirio broke her stare to Kisuke and turned her body to lay down on her back and get some relaxation, "If the natural order itself was changed, then those that didn't change with it will be deemed to be breaking its rules."
'Change the natural law itself? That's possible for her?' Kisuke thought to himself. After all, those who are not fully affected by the natural laws are the Transcendents since they rewrite the reality around themselves for their own benefit, 'But she's not a Transcendent... What's the price for this?'
While Kisuke was having a bad premonition, Kirio continued speaking in the eerily quiet chamber, "It doesn't really affect those who are very close to death, but the fate of those with overflowing life like you will instantly be reversed. Meaning, those who are very lively will instantly experience death and will soon cease to exist."
Kirio paused for a moment before sighing, "This is the first time I've used this... But also the last."
Kisuke's eyes widened and finally understood the price she had to pay, 'Dang it... As expected. She's very loyal to the Zero Division.'
As Kisuke guessed, Kirio first had to experience the reversal before she could pass it on to her target. As a result, she could only use this technique one time since there wouldn't be a second time.
Kisuke wanted to grit his teeth but his numb face didn't even allow that. Still, even without looking, Kirio could feel the frustration from Kisuke's stare, "I'm sorry that it has come this way, but you and I are standing on opposite sides. I had a mission to fulfill."
'What are you apologizing for!?' Kisuke shouted internally, but as expected, Kirio didn't know him enough nor the changes he went through to feel that.
Nevertheless, Kisuke soon calmed himself and closed his eyes, 'Tiamat, what ability of yours do I need to use?' He's on the verge of death, but it's not like that's anything new.
[I may not be as good as my sister, but I still have control over the aspect of life.]
'I don't need riddles now, alright? Explain it to me like I'm twelve... That has difficulties processing things.'
[Even if you say that...] Tiamat doesn't really know how to fulfill Kisuke's request because she never really talked to a 12-year-old Human and doesn't really know how they think. However, it's also true that she has to relay as much information as possible for Kisuke to have a chance to get out of this predicament, [I'll do my best but I can only explain what I can understand.]
[Before I explain it further, I want you to concentrate and go back in time to recall our first clash. The time I reached the surface.]
'Alright. What about it?'
[The black mud under my feet. It was the Sea of Life that I conjured to create and convert all life to my liking. Although it was tainted by Chaos that makes all life sprung from it chaotic and destructive in nature, the underlying law within it is still the same.]
'...' Kisuke went quiet as he thought back to that instance. Even in the middle of a big fight that would decide the fate of the world, he didn't forget to collect some samples of the so-called [Sea of Life].
And sometime after the battle against Chaos, Kisuke tried studying it. Unfortunately, it already deteriorated so he didn't get much from it aside from the fact that it was a concentrated Magic Power and Divine Power that meshed in a very messy way. Kisuke concluded that the Magic Power and Divine Power were just a byproduct as a result of it losing its power.
Aside from that, his only other source of information was Serafall who temporarily froze it, albeit, with great difficulty even in her Super Devil form, and Yoruichi who fought the artificial beings it created.
Kisuke was in the middle of thinking when Tiamat interrupted him, [As I've said, you're thinking too hard. When it comes to natural laws, it's not about how you circumvent them, but how you make them your own. Sea of Life, the ocean where all life sprung out. Now if you associate the sea as the source of life, where does it end? Where does it return?]
'...earth?'
[That's right. Life returns to earth. But as it returns, it also nourishes other lives in their vicinity.]
'This is strangely philosophical.'
[That's why I'm telling you to get away from the world's logic because it is the world imposing its natural laws on you.]
'...This is impossible, isn't it? Especially for someone like me.'
[How so? You've been doing it already for quite some time.]
'...Hmmm?'
[Didn't it occur to you? You Shinigamis are already imposing your own laws through your Zanpakuto when you achieve your Bankai. Think about it, when you use Benihime, you manipulate various objects, are you not?]
'But that's only under the premise that I understand the underlying logic behind them and can only modify them under the same set of rules. And those rules don't break the laws of the universe.'
[That's true. But what makes it possible for you to do something like that in the first place?]
'...Benihime's ability?' Kisuke felt like he returned to the time when he was still an ignorant child.
[That's correct. Now you just have to apply it the same.]
'...Huh?'
[You didn't receive any instinctual instructions to use my ability like you did with Benihime, however, you can approach my abilities as if you did.]
'And how do you propose I do that? And all of those long-winded words just to say use your abilities like I do with Benihime's?'
[There's a way, but I first had to make sure that your mentality is in the proper place before we proceed. Otherwise, you'll die faster with your head exploding into a million bits and no amount of regeneration would be able to save you from true destruction.]