The apartment had a specific place to train in the sunlight, so Klaus didn't have to move from place to place.
As his punches came out and he pushed his muscles and bones to the limit, he could see the positive energy entering his body.
'Last night, there was a lot more cursed energy, but right now, the cursed energy is not as numerous. There is an abundance of positive energy during the day but an abundance of cursed energy during the night. I wonder if the day and night have something to do with each other or if it's something else.' He thought.
As he trained, he also tried to make the cursed energy inside him slowly form what he wanted—the star it should form.
Perhaps this was another reason why now his ability had gotten out of control, for when he first used cursed energy for the first time and in large quantities, he had not yet completed his tunnels for the movement of that energy.
Moreover, during the night, and because of this ability, not only can he not train, but he can also not use positive energy, let alone make the cursed energy go round and round. The night at this time, rather than a powerful ally, is a dangerous enemy.
But since the skill ended in the morning, he noticed that the movement of the cursed energy was now faster. Those circular movements were now completed at just over 1 per minute, a considerable improvement considering that making half a turn in 1 minute was complicated before.
But it was still insufficient. He still needed thousands of turns to reach 10,000. That's why Klaus focused on training while unconsciously moving the energy internally.
The amount of positive energy in this place was incredible, so his training slowly began to have amazing effects on his body.
Strengthening his muscles and bones was just one of those improvements. He even felt that his mind was improving.
But, the most noticeable improvement was in his energy.
To put it in context, Klaus has very little positive energy. He has so little energy that if he were stretched enough to form a large cloth, the cloth that would come out would be practically invisible. That means he had little density in his positive energy.
It's an issue that he had already realized since he was in the Cursed World; he realized it the moment he saw that guy show his realization.
The density of the energy that person had allowed you to see the shield that he formed in front of his body, with a yellowish color.
In Klaus, that was not the case. If he formed the same shield all over his body, it would be almost imperceptible, and that was not good, even if it looked like it was. This was because the more imperceptible it is, the weaker it is.
So, he needed to increase the density of his energy, and for that, he needed positive energy in large quantities.
And that was the most noticeable improvement. At this moment, he was striking with his hands surrounded by positive energy, making the strike much more powerful. This, together with the now 60 degrees of activation of his gravity, made the amount of energy coming to him more and more abundant, slowly making his energy denser.
Dense energy has many pros and no cons. Klaus was satisfied.
While training, he also tried to understand the energies more thoroughly.
'I think positive energy is not as good at delivering blows. I feel like it's more passive, and its punches are softer.' He thought.
Suddenly, something occurred to him: Could he strike with the cursed energy and thus strengthen his positive energy? He wondered because the cursed energy, although it did enter his body now, remained inactive most of the time.
And after about four hours of intensive training, the cursed energy stopped entering him. Looking inside, he realized that his Cursed Core was full of energy; it could no longer enter, so he stopped accepting the energy.
'So this is the mechanism... There is a container in there that I must fill. That container will be my reserve energy, while the energy in the body is my power. That has a problem, though.' Klaus frowned and paused for a moment to think.
'If there are two containers, the Core and my body, what will happen when they fill up? Won't I be able to absorb more cursed energy?' he thought.
'No, wait.' Suddenly, he realized something he already knew. 'Right, it's density. Theoretically, density tends to infinity sometimes. Maybe here, too. And while infinity is not always the answer to physics questions, this world, governed by physics and fantasy rules, perhaps has special situations. It seems I have yet to investigate.' Klaus smiled.
Originally, he thought there might be a limit of strengthening, but when he realized this, he immediately understood that, while such a limit might exist, it was too far from it.
Now, there was an additional problem.
'Why isn't the density in the core increasing? Is there something special, or is it due to a problem because of my ability?'
After thinking so, Klaus continued his training and focused on moving the cursed energy into the Core. But he couldn't get it in there.
There was a problem. The density there was not increasing, although the energy itself in that place was much denser than in his body.
After trying for another hour, he gave up and sighed. 'Forget it. When I solve my ability problem, I'll try to do it again. For now, let's focus on training positive energy.' He thought.
And obviously, he would try to train now using cursed energy, which was why he came here.
'I think I can already move some of the cursed energy to my hands...' He thought and tried to do so. A few seconds later, his hand was surrounded by a cold, deadly, slightly dark energy. He had to make more of an effort, as he still hadn't formed the base he needed, but all in all, he smiled.
He immediately pounded his forehead with determination.
He did it several times in a row in a moment, and his beautiful purple eyes glowed with curiosity.
'The punch is quite a bit more powerful than with positive energy and attracts more energy.'
He could see the positive and cursed energy rushing into his body. The cold energy couldn't get in, but the hot energy did.
But as he looked inside his body, he frowned.
'Although there is a slight difference, as I can reach further at my 60-degree angle, but... It's so minimal that I feel it's not worth the effort. I'll get tired faster and end up only getting a little stronger. I think the quickness of the strike and the less effort I have to put in with the positive energy wins out this time.' He thought.
He gave up on this issue and again switched his energy to positive to continue his training.
Thus, his training went from morning to evening. He stopped to eat a little before continuing the intensive training that pushed his muscles to the limit.
During the night, he stopped the training as his ability forced him, so he focused on investigating more about his inner self and his own body, in addition to his abilities.
He substantiated several theories in one night, as no one disturbed him, and he didn't have to hide, as no one came to his house.
That is until the next morning, the day of the mission.