*One Piece: A Side Story – The Forgotten Isle (Part 6)*

Luffy stood at the bottom of the pit, his usual carefree grin replaced by a hint of confusion. The walls around him began to close in slowly, the stone grinding against itself. "Uh, guys... I think I messed up!" 

"Hold on, Luffy!" Nami shouted from above. She rushed to the edge of the pit, looking down at him. "We have to think this through!" 

But it was too late. The rumbling intensified, and the stone around Luffy began to rise. Suddenly, the walls of the pit split open, revealing a vast, dark chamber deep below. The blue glow from the earlier runes flickered dimly, casting eerie shadows across the room. 

Luffy's curiosity got the best of him. Without a second thought, he leaped down into the chamber below, landing with a soft thud. "This is definitely where the treasure is!" he shouted, his eyes lighting up. 

The rest of the crew scrambled to follow. Zoro was the first to leap down, his swords clanging against the walls as he landed. "We should've known Luffy would rush in like this." 

Robin stepped carefully around the chamber, examining the markings on the walls. "This room is unlike any other I've seen. These are symbols from a forgotten age... This island isn't just a treasure trove; it's a prison." 

The cloaked figure, who had been standing silently in the background, stepped forward. "You've entered the heart of the island. What happens next is in your hands." 

The moment the figure spoke, the stone doors at the far end of the chamber slowly creaked open, revealing a massive stone altar with a shimmering object resting on it. The glow from the altar pulsed rhythmically, like a heartbeat. 

Luffy's eyes widened. "There it is!" He began running toward the altar, but suddenly, the entire chamber shook violently, as if protesting his movement. 

"Wait, Luffy!" Robin shouted, but it was too late. 

As Luffy reached the altar, the ground cracked open beneath him, and an enormous shadow began to rise from the depths. 

"Only those worthy may claim the power," a deep, booming voice echoed throughout the chamber. 

To be continued...