In Theory [Senku x Reader]

0.1 | A Message Through Time

He was up to something no nine-year-old should probably be doing.

If not for the relentless wind muffling the sharp clinks of metal, the three of you would've been caught by now. No doubt about it.

"Nice, Senku! Another neat science doohickey?!" Taiju pumped both fists in the air as he watched Senku assemble the metal poles. "What's the big experiment this time?!"

Senku smirked, barely paying attention as he haphazardly pieced the contraption together. "This's just a simple amateur radio."

You shot him a dry look before glancing at the setup. A few support beams for structural stability, a set of antennas for wave transmission, and a series of inward-facing parabolic reflectors designed to capture signals—all interconnected by a meticulous web of wires. By Senku's standards, this was rudimentary.

Then again... most nine-year-olds didn't build fully functional long-range communication devices and call them amateur models...

You sighed, already resigned to your inevitable role in this madness. Digging into the second bag, you pulled out the remaining components and started assembling them alongside Senku, your hands moving on autopilot after helping him build a test model just weeks ago. Though, back then you should've known it was for a greater purpose.

As you secured an antenna into place, you cast him a sideways glance, eyes narrowing. "And this is for...?"

Senku straightened, balancing the nearly finished contraption with one arm like it weighed nothing—though the faint tremor in his muscles didn't escape your notice. His usual smugness practically radiated off him.

"This baby? It's gonna intercept a message from the future—if temporal signals even exist."

You didn't even need to turn your head to visualize Taiju's reaction.

"This is so stupid," you muttered, suppressing a shiver as another gust of wind sliced through the air.

"Correction," Senku called over the howling wind, fingers deftly adjusting the tangled mess of wires. "This is science."

Taiju, ever the enthusiastic one, finally caught up to the weight of Senku's latest revelation and practically started bouncing in place. "The future?! Wait!" His head whipped between the two of you. "Who in the future?"

'Who indeed.' You sighed, slotting the last of the components into place.

Senku crossed his arms, smirking. "Me."

Taiju tilted his head, his face scrunching in confusion. "Huh? I'm a little lost..."

Honestly? You doubted it was just Taiju.

With the radio finally balanced on the Skytree's steel framework, Senku turned to face you and Taiju, the city lights below casting a flickering glow through the shifting folds of his clothes.

"Get excited for this test..." He raised two fingers—the same signature gesture he always used when working through calculations or dropping a mind-blowing revelation. "Because we're about to find out if future me ever cracks time travel."

From somewhere in the distance, you swore you could hear the faint toll of temple bells.

Senku, ever the scientist, carried on without pause. "You wanna know why I picked today?"

"Why?" Taiju asked, tilting his head.

"Because it's New Year's?" you guessed, without much thought.

"Exactly! Ten billion points!" Senku grinned, clearly pleased with himself.