Karou was in his mental field, inside he removed his Chakra to the outside, he would do the same thing that Naruto did with Kurama, a kind of tug of war, of course it would be much simpler the beast was already dead and helpless. Soon Karou held the Nucleus and entered his mental field.
Inside he easily pulled the Chakra from the core, as soon as the Chakra came out it took the shape of a boar, Karou did not let the boar enter his body. The boar's chakra was so small that it was not even worth absorbing at this point. It also did not serve as a kind of backup battery, as it was not a concentrated Chakra that would soon dissipate.
Karou continued to absorb the apprentice-level Cores without elements, so he managed to create a fist-sized Chakra ball. It was time to absorb it. Karou took the Chakra and placed it directly in the navel area where the First Chakra gate and the main point after the heart were.
Instead of making that Chakra a secondary part of the body as Naruto did by creating his Chakra cloak, he merged it into his own chakra as the other Jinchuriki did. After a long time of research Karou discovered the reason why only Naruto had a chakra cloak.
The Jinchuriki joined the chakra of the beast with tails, while Naruto used the chakra in a secondary way, this form was often more effective, but it was also unusable by those with low Chakra reserves or when the amount of Chakra was very low.
The benefits of this were that even using the entire Chakra of the beast Naruto could continue fighting, if the beast was removed Naruto could survive for large amounts of time, besides the dominance and control of a secondary Chakra is much better than the dominance of the Chakra itself gigantic.
The disadvantage is that this could only be done with a tailed beast, other beasts would not have such a large amount of Chakra to spend. Karou finished merging and felt his reserves overload, he didn't have the vitality of a beast to continue living.
He then transferred the excessive amount of Chakra into the system as soon as it reached its limit. The system gained a lot of energy, Karou's own body emanated Chakra into the surroundings making the cave a great training place.
Karou then began to meditate to fill his reserves again, after recovering his lost chakra and resting Karou opened his eyes, he felt his reserves almost double in size.
- Jutsu multi shadow clones! - Karou shouted the name of the technique, he felt his chakra subdivide a dozen times, then there were almost a hundred of himself standing in the water.
Karou looked at that and screamed happily, there were more than 60 clones, it still didn't compare to the naruto in the Classic, even though it was more than most people would have in their entire life. Karou had reached the Tiger level.
Karou undid his clones and felt the Chakra return to his body, he then took the cores of the Grand Apprentice, he left four clones, the process seemed short, but in fact it had lasted for days, so the five sat in a circle facing the side from outside with the nuclei in the center behind them and went back to meditating.
After many days Karou made another breakthrough, there were far fewer Great Apprentice cores, but the amount of Chakra in them was much greater than those of the Apprentice Level. Karou then spent a month absorbing the Cores inside, his number of clones had exceeded one hundred.
Karou just ate snakes and drank water, he started to look like a beggar, at least he didn't stink because of the boiling water, he also tried to meditate in the water to increase his resistance and breathing abilities, so the hot water didn't hurt him anymore .
Karou then saw his final challenge, absorbing the Red Wolf Core. After a long time removing the Chakra from the Core, Karou began its absorption, after hours of the same process he finally sucked the entire Chakra, getting rid of the excessive amounts.
After that he got a surprise, Karou got up and didn't believe in what he could do, he undid the clones, he sucked the air from the surroundings as much as he could, concentrated his Chakra and aspirated.
A fireball the size of a basketball came out of his mouth and hit the water, there was no vapor after that water was special, Karou was incredibly happy, he could learn the jutsus from the beasts he absorbed. Jutsu was not a big deal, but it was a great base to learn the Fire style, fireball jutsu of the Uchiha Clan. Karou was going to leave the hunting ground at this point, he sat down and went back to meditating to restore his Chakra reserves.
He then felt a strange movement inside the cave, his fire was extinguished, he felt a penetrating murderous intention, Karou quickly activated his Sharingan. In front of him he saw a hissing tongue, the owner of the tongue looked at him with curiosity and strong murderous intent. A huge snake, only its head was more than two meters.
Karou saw that absurd amount of Chakra, he didn't recognize that species, he didn't know his opponent's strength, but in front of him Karou looked like an ant, this beast was as strong as the Lion he saw in the forest. Probably a Dragon-level beast.
It had purple scales, Karou couldn't see his whole body, his body came out of the boiling water, at this moment the giant snake opened his mouth, Karou was scared at this moment, but to his surprise a scroll was the only thing that left
It was a scroll with several names, Karou recognized that scroll.
- Would you like to make an invocation agreement with me? A solemn voice came from the snake in front of him.
Karou felt incredibly surprised, such a strong being wanted to be his invocation. Karou did not know why, but the beast showed no hostility, his murderous intention was natural to his body and could not be hidden. The snake just looked curious and impressed.
Karou knew that the Invocation Contracts had no disadvantages for the subscriber, only the contractor could be taken to inconvenient situations, so only trusted people received their contracts.
Karou decided to accept, since he didn't think he could refuse.