One Piece: I will become stronger by checking in

Suddenly, Kai opened his eyes. His usual golden pupils had vanished, replaced by a pair of blood-red eyes.

In an instant, an intense wave of murderous intent swept over the area, making everyone tremble in fear.

Luffy, sensing the change, grew anxious and called out, "Kai... Kai?"

Kai's blood-red gaze locked onto him. In that moment, Luffy felt like he was staring into the face of death itself, the sheer pressure making him break into a cold sweat.

Kai spoke with a trembling voice, struggling to maintain control. "You... all of you, go find Nami and the others. I need to be alone for a bit."

His mind was overwhelmed by violent, murderous urges, threatening to consume his sanity. He even briefly thought of killing everyone around him. Fortunately, his immense willpower allowed him to suppress these dark desires, but only for now. He wasn't sure how much longer he could hold them back.

Luffy wanted to protest, but Kai cut him off. "Go! Now!"

After a brief silence, Luffy slowly stood up, understanding the gravity of the situation. "I get it," he said. "Zoro, Sanji, Usopp, let's go!"

Without hesitation, Luffy jumped off the boat, heading toward the village. Zoro, Sanji, and Usopp followed after glancing back at Kai.

They trusted Kai, knowing there was a reason for his warning. If he said they needed to leave, it was for their own good. As strong as Kai was, they believed he would handle it.

Once they were gone, Kai's mind grew hazier, the murderous intent intensifying. He knew he would lose control soon.

"Damn system… what kind of messed-up bug is this?" Kai cursed under his breath as he sprinted toward the shoreline.

When he reached the beach, he dove headfirst into the ocean. But the moment he hit the water, the killing intent fully took over. His bloodshot eyes glowed with malevolence, and his body underwent a dramatic transformation. His clothes turned into a flowing black mass, much like when Luffy transforms into Nika, except his attire became a deep, dark shade.

Black flames erupted from his back, surrounding him, burning fiercely even underwater. His hair changed from black to crimson, and his entire appearance morphed into that of a demon, like something that had clawed its way out of hell.

Nearby sea creatures, curious and unaware of the danger, swam toward the disturbance. But when Kai turned his bloodthirsty gaze on them, they became victims of a brutal massacre.

...

Meanwhile, Luffy's group was in a somber mood. They had just encountered Nami after a confrontation and learned from Johnny that Nami had seemingly killed Usopp.

The heavy atmosphere lingered until a familiar voice broke through.

"What are you guys doing here?"

Everyone turned, surprised and overjoyed.

"Usopp!!!"

...

After a while, the group gathered and Usopp explained the situation. "So Nami stabbed herself to save you?" Zoro asked.

"Yeah!" Usopp nodded.

After a moment of silence, Luffy stood up, determination in his eyes. "If that's the case, then... let's go get our navigator back!"

"Understood, Captain," Zoro grinned.

The crew began marching toward Arlong Park.

At that moment, Nami sat on the ground, her eyes full of despair. No matter what she did, she couldn't stop the villagers from trying to fight Arlong. They no longer wanted her to suffer for their sake, even though it meant certain death for them.

Collapsing under the weight of it all, Nami picked up a knife and repeatedly stabbed the tattoo of the Arlong Pirates on her arm, her screams filled with anguish.

Suddenly, she felt someone grab her arm, stopping her from doing more harm. She turned to see a very different Kai Vane standing behind her, his blood-red eyes devoid of any emotion.

"Kai... what happened to you?" Nami stammered. "Why do you look like this?"

"It's nothing. Just some issue with the system that's causing a bit of trouble." Despite his familiar words, his tone was cold, far different from the Kai she knew.

Without warning, Kai knelt down and pulled Nami into a tight embrace. "Don't worry. I'm here now."

"Nami... Arlong has made you suffer for too long, stealing your happiness during the best years of your life," Kai said softly. "But that ends now. I'll take care of everything."

He stood up and turned toward Arlong's domain. "You're our navigator. You're not running away from this."

With that, Kai shot into the sky, flying swiftly toward Arlong Park.

Nami, watching him leave, couldn't hold back her tears anymore. They poured down her face like a flood, and she whispered, "Thank you, Kai..."

An unfamiliar but warm feeling started to grow in her heart.

Suddenly, a voice called out from behind her.

"Hey, Nami! We're here!"

She turned to see Luffy and the crew approaching, a smile forming on her lips. For the first time, she wasn't hiding her true feelings. She had accepted her heart and the bonds she shared with them, and she wouldn't lose this friendship again.

And she trusted Kai. If he said he would handle it, then she believed he would.

Nami waved and said, "Hey everyone, I'm here!"

The crew looked at her, stunned. Just moments ago, she had been filled with sorrow, yet now she was smiling.

Luffy ran toward her with his usual enthusiasm. "Nami! Let's go take down Arlong and free this village!"

But Nami shook her head. "No need."

"Huh? Why not?" Luffy asked.

"Because Kai's already on his way," Nami explained.

At first, Luffy wanted to ask more questions, but hearing that Kai was involved, he smiled confidently. "Oh, Kai's going? That's awesome! He'll totally crush Arlong!"

Zoro, however, looked uneasy. "Wait... you said Kai's gone already?"

"Yeah, why?" Nami asked, confused by his concern.

Zoro's expression darkened. "Something's wrong. Back on the boat, Kai started acting strange. He was clutching his head, and when he opened his eyes, I felt this insane killing intent from him—stronger than anything I've ever felt."

"So, something must've happened to him. Did you notice anything different about him just now?"

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Power Stones would be appreciated if you like the story