After spending some more time with Yoruichi, Kisuke finally decided to leave.
"Where are you going for Kuroka and Koneko's training this time?" Yoruichi asked before he opened the door.
"The sea."
Yoruichi wondered how they were going to train their Ki on the ocean, but Kisuke didn't elaborate it any further and just left.
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Kisuke once again said his goodbyes to Hestia and the others, but before they left, Kisuke noticed the forced smile on the former's face, making him wonder what happened when they left them in the gates of Pandemonium. However, he didn't have time and he didn't think it's that serious. If the awkwardness still persisted as he returned, Kisuke will confront her then.
After preparing the teleportation circle, Kisuke first turned to the Nekoshou sisters before activating it, "By the way, did you do the exercise that I gave you last time?"
"Yes, nyaa~. We're finally able to circulate and gather pure Ki through the pores of our skin... After some hardships, nyaa." Kuroka answered while recalling the physical pain they had to go through just to succeed. She and Koneko don't even know what it's even for since it's a lot more efficient and easier to do it through normal breathing, 'Does he want us to go to outer space? But there's no Ki to absorb out there, nyaa...'
Kisuke grinned and a bad premonition instantly bloomed within Kuroka and Koneko. Since he asked about the exercise, both of them immediately started circulating and absorbing Ki through their skin pores before Kisuke activated the Teleportation Magic without adding another word or warning them.
A second later, they were transported to a pitch black place but that's not what concerned the Nekoshou sisters but the very heavy pressure that is pressing on them and their inability to breathe.
Nevertheless, the both of them still had some freedom and couldn't feel any immediate threat from their surroundings so the first thing they did was to conjure light. With combined luminance they finally confirmed where they were and their guess was correct. Around them was the almost opaque dark blue salt water and rock formations with strange creatures crawling on them.
The next instant, they heard Kisuke's voice inside their heads, 'For the next one week, we'll be staying here. For starters, before the both of you drown, learn how to 'breathe' through you Ki.'
'Easier said than done, nyaa!'' retorted Kuroka, 'Doing this on the surface was already hard enough, but we're in extreme pressure where even I could hardly move! Where are we anyway, nyaa!?'
'Be proud! We're the first people to reach the deepest ocean of this world... Probably.', Kisuke jokingly replied but he suddenly disappeared within the darkness where Kuroka and Koneko's light couldn't pierce through while leaving the words, 'After you're able to overcome the breathing problem and pressure as naturally as you breathe, we'll move to the next step. However, please do so before three days have passed or else we'll be behind schedule. Good luck~!'
Kuroka wanted to complain more but Koneko grabbed her shoulder and said while shaking her head, 'Isn't it about time you get used to how he does things, Nee-sama? Besides, I don't think it's that hard. We just have to stay alive with only Ki.'
Kuroka looked at her and replied with her usual smile, 'Come on now, Shirone~ I'm not angry at him, nyaa. I just like complaining to his face... Though he also knows that and just ignores my bullshit most of the time.'
Koneko pressed her lips together in doubt but due to the pressure slowly becoming unbearable as it slowly depleted their Ki reserves, they had to find a way to actively restore them so she stopped arguing with her big sister and sat down on the ocean floor and closed her eyes to concentrate.
Kuroka just shrugged her shoulders and extinguished the lights they conjured since they didn't need it and it'll only attract the strange sea creatures that might disturb them before doing the same thing as Koneko. She didn't want her to do it faster than her since her pride as a big sister would be wounded if that were to happen.
Kisuke watched their progress from afar while quietly fending off the ancient monsters that lurked within the darkness of the ocean, with one of them even spanning as long as Great Red. He didn't want to kill them, because he didn't know what kind of consequences their sudden absence would result in for the ecosystem that was already balanced by time.
'Unlike Serafall and Sona, what they need to achieve is just a complete integration of their own attributed Ki, Physical body, and Soul. Since this is outside of my expertise, I can only help them with their Souls and what they do next would be entirely up to them. In any case, they should have more options open up for them.'
Kisuke could have awoken Sona's ability and given her more concrete and specific instructions to use and improve it, but as much as he want to direct everyone to the most efficient way to get stronger, he knew he absolutely can't do that, As that would not only just impede their future growth, but also their own creative thinking. Whatever they believe is the best, he'll support them as much as he can, no matter how stupid it sounds. That much trust is what he needed to put in them.
In the meantime, Kisuke took out the Phosphoplasm that he secretly collected from Sona to study and confirmed if it's really the material that he knew from the Hell of his previous world, 'If I'm lucky, I will be able to return much sooner. I just never thought that it would be through studying accidental particles and Dragons.'
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Two full days later, Kuroka and Koneko both opened their eyes and around them was a white aura tinged by their own Ki's color with Koneko blue and Kuroka red. Right now, they are fully capable of 'breathing' through the use of their Ki and could actually indefinitely stay alive as long as they could absorb the Ki within their surroundings, if not for the heavy mental strain they were subjected to doing this exact thing.
Despite looking just fine, they were actually already very tired and lightheaded. Since they had to manually control this breathing, the time they could do this was still very limited and this limitation would only be lifted if they could do this unconsciously.
But just as Kuroka was about to complain for real due to the imminent danger they are about to face if they were not allowed to take a bit of rest, a bubble suddenly expanded and enveloped both of them, relieving the great pressure on them and giving them room to breathe normally, "Great work and congratulations for achieving something only a few people were able to do in history~ Well, at least those in public records. For now-"
However, Kisuke words were suddenly cut short as his expression became grim, "Rest and wait for my return." he briefly worded before instantly teleporting away.
With an extremely concerned look, Koneko asked Kuroka, "W-what happened?"
Kuroka immediately hugged her baby sister to comfort her, "I also don't know. But whatever it is, since he asked us to wait for his return, it's not something he can't resolve. Let's trust him, alright?"
Koneko hesitated but nodded her head after a while. The thoughts of following him back were pushed to the back of her head.
Kuroka, on the other hand, despite appearing calm, was also very nervous as it was very rare for Kisuke to make such a face, 'It's probably about Irina-chan and Akeno-chan... I hope they're okay...'