The ruins lay silent beneath the orange sky of Helheim's borderlands.
Broken stone pillars leaned at odd angles, half-consumed by alien vines and crystalline growths that pulsed faintly with life. This was once a place of study—perhaps even worship—but now it was nothing more than a forgotten scar between worlds.
Kouta Kazuraba, Kamen Rider Gaim, stood near the center of the ruin, arms crossed as he stared at the object floating above a cracked pedestal.
A blue crystal sphere.
It hovered without support, smooth and flawless, its surface swirling like liquid glass. Inside, faint lights moved—slow, deliberate, almost like stars trapped in a tiny sky.
"This thing…" Kouta said quietly. "It doesn't feel like Helheim technology."
Across from him stood Seestern.
She looked exactly as she always did—silver-blue hair flowing down her back, eyes sharp and thoughtful, her presence calm yet heavy with unspoken history. She stepped closer to the sphere, careful not to touch it.
"It isn't," Seestern said. "And that's what makes it dangerous."
She circled the crystal slowly, observing the faint runes orbiting inside it. "This is not a weapon. It's a key."
Kouta glanced at her. "A key to what?"
"To the multiverse," Seestern replied. "Or more specifically… a way to cross it."
Kouta stiffened slightly. "Cross it without turning into energy dust?"
Seestern allowed herself a faint smile. "Exactly."
She straightened and met his gaze. "Most beings can't survive multiversal travel. Their bodies fracture, their souls misalign, or their existence collapses under conflicting laws of reality."
Kouta remembered stories—worlds destroyed simply because something foreign tried to enter them.
"So how do you do it?" he asked. "How did you, Joun… even Shadow Moon?"
Seestern's expression softened—but only slightly.
"I don't fully understand it myself," she admitted. "But I know why it works."
She reached into a small vial at her waist. Inside shimmered a faint, glowing liquid—almost silver, almost blue.
"My blood," she said plainly.
Kouta's eyes widened. "Your blood lets people cross the multiverse?"
"Not freely," Seestern corrected. "And not safely… unless it's used properly."
She closed the vial again. "I gave a small portion to Joun. And to my husband. That's all."
"Why not others?" Kouta asked.
Her gaze hardened instantly.
"Because it should never be used casually," she said. "My blood carries the resonance of Flammed, my home planet. It harmonizes with unstable dimensional boundaries—but in the wrong hands, it could tear worlds apart."
Kouta nodded slowly. That made sense. Too much power, too easily shared, always led to disaster.
He looked back at the crystal. "So this thing probably needs something to activate it."
Seestern followed his gaze.
"Yes," she said after a pause. "I believe you're right."
She knelt beside the broken stone beneath the sphere and brushed away debris, revealing faded markings etched into the floor—circles, lines, symbols that converged toward a single point.
"These diagrams," she continued, "were incomplete in the ruins where we found the crystal. But now I'm certain."
She traced one of the markings with her finger.
"There was a platform. A structure designed to synchronize the crystal with the traveler."
"A bridge," Kouta said.
"Exactly."
He frowned. "Then where is it?"
Seestern stood and scanned the ruin again, her eyes narrowing.
"That… is the problem," she admitted. "The platform is missing. Either destroyed, hidden, or moved."
Kouta exhaled. "So even if this crystal can open portals, we can't use it yet."
"Not safely," Seestern agreed. "Without the platform, the crystal would rip the traveler apart—or worse, tear open a permanent fracture between universes."
Silence fell between them as the wind whispered through broken stone.
Finally, Kouta clenched his fist. "Then we search."
Seestern turned to him.
"We search again," he said firmly. "If Ryoma Sengoku is moving across universes, then this platform matters. A lot."
A faint spark of approval crossed Seestern's eyes.
"I was hoping you'd say that," she said. "Because if this crystal exists… then others like it may exist too."
She looked back at the floating sphere, its inner lights pulsing slightly brighter, as if responding to her presence.
"And if Ryoma Sengoku learns how to activate it first," she added quietly, "the damage won't be limited to one world."
Kouta nodded, determination settling into his expression.
"Then we don't let that happen."
Above them, the blue crystal pulsed once—slow, deliberate—like a heart beginning to wake.
And somewhere far beyond their world, the multiverse shifted.