Beyond the sliding bookshelf lay a long, curved staircase that spiraled down into the depths of the manor. The dim light barely illuminated the steps, which seemed to stretch far beyond what the eye could see. Kosu felt a knot tighten in his stomach as he gazed down the seemingly endless descent.

He gulped, recalling the hidden elevator in the garden that had first led him underground. This staircase felt eerily similar, a passage into the unknown. "Riku, I think this leads to the underground chamber," he said, his voice echoing softly in the stillness.

Riku raised an eyebrow, her expression curious. "Didn't you say you had already been there? Shouldn't you have met Miko down there?"

Kosu shook his head. "The underground chamber spans from the manor to the servants' section. It's vast, and I can't help but wonder if there are places I didn't discover." A sense of unease washed over him, mingling with the anticipation of what lay ahead.

After a moment of silence, Kosu and Riku exchanged determined nods. They couldn't turn back now. With a shared resolve, they began their descent down the staircase. Each step was deliberate, the air growing cooler and heavier as they ventured deeper into the manor's hidden depths.

The walls were lined with old stone, and the faint scent of dampness filled their lungs. Shadows danced around them, flickering in the dim light, and Kosu felt the weight of the manor's secrets pressing down on him. Together, they ventured further into the darkness, their hearts racing with the promise of discovery and the hope of finding Miko.

As Kosu and Riku reached the end of the staircase, they stepped into a vast underground chamber that took their breath away. The dim light from flickering sconces cast a warm glow, illuminating the stone walls adorned with intricate carvings of ancient symbols and scenes from the manor's long-forgotten history.

The chamber was expansive, with high ceilings that seemed to stretch into the shadows above. In the center of the room stood a large circular platform, intricately designed with elaborate patterns that mirrored the symbols they had seen in the painting. Surrounding the platform were several archways leading to darkened corridors, each one hinting at more secrets hidden within the underground labyrinth.

Kosu's eyes widened as he took in the surroundings. "This place is massive," he murmured, awe-struck. "I had no idea it was this big."

Riku stepped forward, her curiosity piqued. "Look over there!" she exclaimed, pointing to a large stone altar at the far end of the chamber. Upon it lay a collection of artifacts—old books, peculiar trinkets, and what appeared to be relics of great significance.

As they approached the altar, Kosu felt a chill run down his spine. One item in particular drew his attention: a shimmering orb that pulsated with a soft blue light. It seemed to hum with energy, and Kosu could almost feel its power calling to him.

"Do you think Miko could be here?" Riku asked, her voice barely above a whisper as she examined the artifacts. "What if she discovered something important?"

Kosu nodded, scanning the room for any signs of their friend. "We need to search for her. She might have left clues behind."

Just then, a soft rustling echoed from one of the nearby archways, causing both of them to freeze. Shadows flickered in the corners of the chamber, and Kosu felt a surge of apprehension. Whatever lay in the darkness was not just a remnant of the past; it might still be very much alive.

"Stay close," Kosu instructed, gripping Riku's arm gently as they prepared to investigate the source of the sound. The underground chamber was a treasure trove of secrets, but it also felt like a trap, and they needed to tread carefully.

Kosu and Riku continued down the winding staircase, the air growing heavier with each step. As they descended, they passed through a small room containing a stone tablet inscribed with an ancient language. The markings were indecipherable, but their presence added to the sense of foreboding that enveloped them. With little time to linger, they pressed on, the dark energy thickening around them, suffocating and oppressive.

As they approached the entrance to a large chamber, the sinister energy intensified. Kosu felt a weight on his chest, as if unseen hands were pushing him back. He exchanged a glance with Riku, both of them aware that entering this room would be a struggle.

"Are you ready?" Kosu asked, his voice steady despite the unease creeping into his mind.

Riku nodded, determination etched on her face. Together, they took a deep breath and pushed forward, but it felt as if an invisible barrier resisted their every move. They stumbled, fighting against the force that seemed to claw at them, trying to pull them back into the darkness behind.

"Keep going!" Riku urged, gritting her teeth as she felt the energy swirl around her like a tempest. Kosu clenched his fists, summoning all his strength. With a final push, they broke through the threshold, stumbling into the room.

Inside, the atmosphere was charged with a dark, pulsating energy that seemed to writhe like a living thing. Shadows danced along the walls, and the air crackled with tension. In the center of the room floated a girl, surrounded by ritual tools and intricate magic patterns drawn on the ground. Miko appeared to be in a deep slumber, her expression peaceful despite the chaos surrounding her. The dark energy raged, swirling like a storm, yet she remained undisturbed.

Kosu and Riku gasped at the sight, the unthinkable scene filling them with a mix of awe and dread. Just then, a familiar voice broke through the haze.

"Kosu?! Riku?!" Miko's voice brought them back to reality, snapping them from their reverie.

"Miko! You're here?!" They rushed toward her, relief flooding their hearts.

"I came through the hidden stairs behind the library shelves," Miko explained, her voice steady despite the chaos. "I reached this place before you, but I was caught up in what happened here." Her brow furrowed as she recounted, "Then a monster appeared—a jailor with a massive sword."

Kosu's heart sank as he recognized the description. "I encountered that monster in the underground prison. It must be guarding important locations."

Miko nodded, her expression grim. "I couldn't fight it. I'm a medic and a supporter, not a warrior. I tried to slow it down, to survive. But then... something happened. The ground rumbled, mechanisms activated elsewhere, and the monster vanished into thin air."

Kosu felt a mix of admiration and concern for Miko. "And then?"

"I hid behind one of the columns to treat my wounds," she said, her gaze flickering to the patterns on the ground. "I didn't know if you would come or if I'd be trapped here forever."

The three of them stood together, the energy in the room still swirling around them, but with Miko awake, they felt a renewed sense of purpose. They needed to uncover the truth behind the dark energy, the rituals, and the sleeping girl at the center of it all. Together, they would face whatever danger lay ahead.

As Kosu stood in the room, the warmth of the ring in his pocket suddenly intensified, causing him to instinctively pull it out. He held it up to the dim light, watching as it glowed faintly.

Miko's eyes widened at the sight. "That ring! It's the key to the ritual," she said, her voice tinged with urgency. "The tablet from before spoke of it: 'It's the vow that connects life and death, the realm of ours and what lies beyond.'"

Kosu felt a chill run down his spine. "I found this ring in the prison. A woman held onto it even after death," he explained, recalling the eerie encounter.

Miko's expression shifted as she connected the dots. "I remember! When I examined the study, there were references to a ritual involving Duke Valet and Marquess Bedford. This ring must be tied to spells only available to the nobility."

Riku glanced at the girl floating in the center of the room. "Do you think that girl over there is the Duke's daughter?" she asked, her voice barely a whisper.

Miko's eyes filled with sadness as she nodded. "I think it's her."

Kosu's heart raced, but he fought to remain focused. "Hold on," he said urgently. "I know there's more to uncover about the secrets of the manor, but we must get out of here. Thorn and Jenna are in danger; they could fall under Cistar's influence."

Miko and Riku exchanged glances, understanding the gravity of the situation but feeling lost in the fog of uncertainty. "But how do we escape?" Riku asked, her voice trembling.

"If this ring is important to her, we should bring it to her!" Kosu declared, determination surging through him. He stood up, gripping the ring tightly. "I'll take it to the Duke's daughter."

"It's dangerous, Kosu!" Miko protested, concern etched on her face. "We don't know what that energy will do!"

Kosu met her gaze, his resolve unwavering. "I've been outside; we're trapped in a strange dimension. This is the only way!" He took a deep breath, the weight of the moment pressing down on him.

With steely determination, Kosu approached the floating girl, the raging dark energy swirling around her like a tempest. He could feel its pull, trying to draw him back, but he pressed forward, each step a battle against the oppressive force.

"Stay close!" he called back to Miko and Riku, who watched with bated breath. The air crackled with tension as Kosu fought against the unseen barrier, every instinct screaming at him to turn back.

But he was determined. He had to reach her, to deliver the ring and bring some semblance of peace to the chaos surrounding them. With every ounce of strength he possessed, he pushed through the raging power, determined to succeed in this perilous quest.