10

The master of the Naberius family glares at Kuroka, his eyes flashing with anger. He takes a deep breath and begins to speak in a harsh, authoritative voice:

"Looks like you saw one of the hidden labs, amazing isn't it? These experiments provide feedback and knowledge to progress tests done on chosen people like you. Those random low-level devils are provided by the Old Faction Devils, and do not worry that secret lab is probably cleaned by now, there is a sensor who informs them if some lab is compromised, so they can erase any clues over that place."

"Kuroka, you know very well what you did wrong on your way to get here. You killed all those who worked on our most important project, without thinking about the consequences. Your foolish actions were an unforgivable betrayal against our family and our ideals."

He pauses for a moment, assessing Kuroka's expression. "But you're not the only one to blame. Your sister, Shirone, also has a share of responsibility for all this. She was born destined to be an experiment, just like you and your mother, but we never tested her because you showed an extreme aptitude becoming an high-class reincarnated bishop with 2 devil pieces for our path, however its results are no longer needed. But know that I am a fair man, Kuroka. And to ensure that justice is done, I will use your sister as my new guinea pig. She is young, healthy and you will certainly be a much better test subject than you ever were. I am doing this for the sake of the illustrious Naberius family, Kuroka, you understand the importance of this project to our family supremacy and your sister's future strength, so smile and rejoice, my parting gift to you will make your sister shine. And when your sister have the honor of becoming my new guinea pig, you will see that there is no place for feelings or weakness among the devils of our bloodline whether they be of blood or reincarnated."

The master of the Naberius family smirks as he approaches Kuroka. "You are a fool, Kuroka. If you had just cooperated and followed my rules, you would not have had to suffer and would have been able to contemplate the beauty of my project's success."

"It's a pity that I won't have your assistance anymore, but your sister will serve as a good substitute. With her, I'll be able to reach new frontiers in the power of transcendental devils. And you, Kuroka, will only be a dark reminder of our family's past. But I have to deal with you first. Prepare to face the wrath of the Naberius family!"

Kuroka approached her master, feeling a mixture of tiredness and hatred. She knew this was going to be an uphill fight, but she was determined to win.

Kuroka moved swiftly across the battlefield, dodging her master's attacks with grace and dexterity. She knew she would have to use all of her senjutsu and youjutsu skills if she wanted to stand a chance against him.

The master of the Naberius family was in a defensive stance as Kuroka charged forward with a swift attack, her feet skilfully dancing across the ground, while her claws glowed with demonic energy and black flames.

The fight continued intense and violent, with both sides exchanging powerful blows. Kuroka moved quickly, dodging her master's attacks and launching precise attacks with her claws. The Naberius family master, on the other hand, lashed out with demonic energy, causing powerful explosions that sent Kuroka flying through the air.

Kuroka leapt into the air, slashing with her right claw. Her master deftly dodged, and Kuroka fell to the ground with a dull thud. Without missing a beat, she quickly got up and launched another attack, but her master was ready for it, and blocked it with a blast of demonic energy.

The two fighters traded blows for some time, with Kuroka using her senjutsu and youjutsu skills to disorientate her master. She created illusions of herself and released a poisonous mist, forcing her opponent to fight blindly.

However, her master was an experienced fighter, and didn't fall for Kuroka's traps. He used his skill in demonic energy manipulation to launch powerful energy beams at Kuroka, forcing her to retreat.

But Kuroka wasn't an easy fighter to beat. She continued to attack with fury, her resolve unshakable. Her strokes were swift and deadly, and she moved with deadly grace, her beauty belying her ferocity.

The fight continued for a while, until a voice suddenly came out: "Keep attacking Kuroka!" Kuroka looked around in surprise, but didn't have time to react as her master took the opportunity to attack with everything he had.

Kuroka tried to dodge, but was hit full on by a devastating blow. She staggered back, her body covered in wounds and blood. But even in her weakness, she rose, her hatred still strong.

She launched one last attack, her body glowing with demonic energy and black flames enveloping her claws. Her master tried to block but it was in vain, strangely he couldn't move as if he was being grabbed in his current position. The attack was so strong that he was sent flying through the air, landing with a crash against a far wall.

Kuroka stood there, her breathing labored, watching the dust settle. She knew the fight wasn't over yet, but now she had a chance to win.

Despite being exhausted, Kuroka continued to fight with determination, using all his skills to try to overcome his master. She knew that the battle would be extremely difficult, but she wouldn't give up easily.

As Kuroka prepared to run and attack her master again, the mysterious voice came interrupting the combat. "Wait, Kuroka," said the voice. "I'll help you, I can hold him in place for you to attack him, let's work as a team, after all he's a high-class devil and you, even being of the same level, is exhausted." Says the male voice.

Kuroka looked around, trying to identify where the voice was coming from. Then, a figure emerged from the shadows. The master of the Naberius family was taken aback by the sudden appearance, but soon recovered. "Who are you? Wait, are you that useless brat who is Rizevim's grandson? The famous useless heir of the Lucifer family, it's nice to meet you, but you should get out of here boy, this place is too dangerous for someone as weak as you are. ' he asked, with disdain.

"And what are you going to do to make me leave? Call my grandpa to drag me home?" Nero speaks in a mocking tone.

"It's a great idea, Rizevim will be happy to hear the results of the project and to be able to punish his disobedient descendant." The master of the Naberius family smirks.

Nero didn't answer anything this time, but instead started raising his arms pointing in the direction of his target. This gesture caused his shadow to be linked with the target's in a straight line, after which the shadow materialized and enveloped the master, trapping him and forcing him to remain immobile.

Kuroka took the opportunity to attack the master, delivering a powerful blow that left him seriously injured.

The master looked at the two with hatred and in desperation tried to scare Nero for a chance to eliminate Kuroka. "You kid, get out of here now and I won't tell your grandfather anything about this. Our families are allies and your grandfather supports my research, are you sure you dare to go against me and your old man?"

"Don't worry, no one will tell him what happened here. That's exactly why you need to die, after all dead men tell no tales." Nero gives a gentle smile to the master of the Naberius family. He immediately, even before the master of the Naberius family could do anything, Nero condensed the power of darkness into a single beam, hitting its target in the same spot where Kuroka had wounded him earlier.

The master screamed in pain as he was hit by the beam of darkness that opened a hole in his chest, and then he staggered and was immediately attacked by Kuroka who dealt the lethal blow by digging her claws into the heart of her now deceased master.

Kuroka looked at the figure that assisted her in the fight, grateful for his help. "Who exactly are you? As far as I know, Rivezim has two grandchildren, the famous strong one recently fled causing an uproar in the underworld and the infamous weak one was put in charge of the Lucifer house." she asked curiously.

The black-haired, blue-eyed demon with a calm and resolute expression. "Well, as you said I am the infamous one, my name is Nero Lucifer", he said. "And I came here to cause trouble for my dear grandfather and in my spare time I was able to help you."