"Minato," Kushina huffed, grabbing the iron railing to haul herself up another step. "Are we climbing to the moon? Because if we are, I need to pack a sweater."
"Almost there," Minato's voice drifted down from above, annoyingly calm and not even slightly winded.
Kushina glared at his back. They were inside the old Fire Watchtower on the western edge of the village. It was a relic from before the First War, a hollow stone cylinder containing nothing but dust, darkness, and a spiral staircase that seemed to go on forever.
The air inside was cool and smelled of old limestone and damp mortar. Their footsteps echoed—clack, clack, clack—a rhythmic, dizzying sound that bounced off the curved walls.
Kushina looked down. The ground floor was a black pit. She looked up. The stairs twisted away into the gloom like a snake's skeleton.
"You said you had a surprise," Kushina grumbled, taking another step. "Usually, surprises involve food. Or at least a chair. This feels like cardio."
"It's about the shape," Minato said. He stopped on a small stone landing near the top, where an arrow loop let in a shaft of moonlight.
Kushina joined him, leaning against the wall to catch her breath. The red hair stuck to her neck with sweat. She looked at him, ready to complain again, but the look on his face stopped her.
He wasn't smiling his usual goofy, apologetic smile. He was looking at her with that intense, analytical blue gaze—the one he usually saved for sealing formulas or enemy combatants.
"The shape?" she asked, her voice softening.
Minato held out his right hand.
"Watch."
He didn't make a seal. He didn't chant. He just focused.
The air in the tower changed. The pressure dropped, popping Kushina's ears.
In his palm, blue light began to bleed into existence. It wasn't the chaotic, explosive mess of the ice pops. It was controlled.
Chakra spun. It flowed in a dozen different directions at once, currents fighting and holding each other in a terrifyingly perfect equilibrium. It roared like a captured typhoon, the sound a high-pitched whirrrrrr that vibrated in Kushina's teeth.
A sphere. A perfect, rotating sphere of condensed power.
The wind from the rotation whipped Kushina's hair back. The blue light illuminated the sharp angles of Minato's face, casting deep shadows in his eyes.
"It's beautiful," Kushina whispered, the red chakra in her own gut stirring in response to the density of the power. "What is it?"
"It's a ratio," Minato said, his voice straining slightly with the effort of containment. "Based on the Tailed Beast Bomb. But... I made it for you."
He let the chakra dissipate. The sphere vanished, leaving the air suddenly silent and heavy.
Minato turned to the railing. He ran his hand along the cold iron.
"Look at the stairs, Kushina."
She blinked, looking down at the dizzying drop. "It's a spiral. Like my clan's crest."
"Right," Minato said. He traced a circle on the flat top of the banister. "A flat spiral goes around and around. It never changes elevation. It's a loop. It's... stagnation."
He looked at her.
"That's how the village sees Jinchūriki, isn't it? A cycle. A vessel contains the beast, the vessel dies, the beast moves to the next. A flat circle of duty and containment."
Kushina felt a cold knot tighten in her chest. He was right. It was the curse of the Uzumaki. To be a jailer until you broke, and then to be replaced.
"Thanks for the pep talk," she muttered, crossing her arms to hide the shiver. "I really love being reminded that I'm a disposable battery."
"But this," Minato said, gesturing to the stairs themselves, "is not a flat spiral."
He walked down two steps so he was standing below her, looking up. The moonlight framed her silhouette against the dark stone.
"It goes around," Minato said, his hand sweeping upward along the curve of the steps. "But it also goes up. It has a third dimension. It climbs."
He reached out, taking her hand. His skin was warm, a stark contrast to the cold iron.
"A spiral that climbs is a helix," he said softly. "It looks the same from above, but from the side... it's rising. It's evolving."
He squeezed her fingers.
"I can't stop the spiral, Kushina. You are the Uzumaki. You are the vessel. That's your burden, and I can't take it away without killing you."
Kushina stared at him, her breath hitching. Most people tried to tell her it would be okay. Most people tried to pretend the monster didn't exist. Minato looked the monster in the eye and acknowledged the weight of it.
"But I can change what it does," Minato vowed, his blue eyes fierce. "I can be the lift. I can make a jutsu—I can make a life—that takes that rotation and pushes it upward. We don't have to just go in circles. We can climb."
Kushina looked at the stairs.
Round and round. But always up.
She looked at the Uzumaki crest on her sleeve. A flat swirl.
Then she looked at Minato. He was the vertical axis. He was the force that turned a cage into a tower.
The cold weight in her stomach didn't vanish, but it felt... lighter. Manageable. Like a backpack she was carrying up a mountain, rather than a stone tied to her feet in the ocean.
"You're a dork," she whispered, her voice thick with emotion. "You brought me to a dusty tower to give me a geometry lesson."
Minato smiled, that sheepish, boyish grin finally breaking through. "I thought it was romantic."
"It is," she admitted.
She looked at his hand, where the blue sphere had been.
"Show me again," she said.
Minato called the sphere back. It hummed to life, lighting up the dark stairwell. The rotation was mesmerizing. A storm held in the palm of a hand.
"It needs a name," Minato said, his face scrunching up in deep concentration. "I've been workshopping a few. I'm thinking: The Spiraling Flash Super Round Dance Howling—"
"Rasengan," Kushina interrupted.
Minato blinked. The sphere wavered slightly. "Huh?"
"Rasengan," she repeated. The word rolled off her tongue, sharp and simple. Spiraling Sphere.
It was blunt. It was direct. It was exactly like her. And it captured exactly what he had just said—a rotation that created a shape.
Minato frowned. He looked at the jutsu. He looked at her.
"What?! That's so boring!" he complained, looking genuinely offended. "There's—there's no flair to it at all! Where's the poetry? Where's the 'Nimbus'?"
Kushina rolled her eyes. She stepped down one step, bringing her face level with his.
"That's what it is, Minato. It's a spiral sphere. Don't overthink it."
"But—" Minato started to argue, likely to propose adding 'Ultra' or 'Legendary' to the prefix.
Kushina reached out. She placed her hand firmly over his entire mouth.
His protests turned into muffled mmph-mmph noises against her palm. His blue eyes went wide.
She smiled, her eyes crinkling at the corners. The blue light of the Rasengan reflected in her irises, making them look like violet galaxies.
"Rasengan," she said again, final and absolute.
Minato looked at her. He looked at the determination in her face, the way her red hair floated in the chakra wind. He sighed through his nose, a puff of warm air against her hand.
He nodded.
Kushina lowered her hand, but she didn't pull away. She leaned forward, resting her forehead against his, the deadly sphere humming between them like a promise.
"Okay," Minato whispered. "Rasengan."