The afternoon sun slanted across the small courtyard of the Tokito household. Kazama Aoi had found two sturdy branches of a suitable thickness and carved them into rudimentary wooden swords, their length perfectly scaled for the twins' small hands.
Standing in the center of the yard, she demonstrated the most basic vertical strike: the draw, the swing, and the recovery. Her movements were crisp and efficient, carrying a sharp, disciplined edge that made the boys' eyes sparkle with wonder.
"Watch closely," Aoi instructed. "A swing doesn't come from the strength of your arms. The power starts in your core—your waist and abdomen—and carries through to your arms. Keep your wrists steady; don't let them wobble."
She demonstrated the movement once more. "Now, I want both of you to swing one hundred times."
Muichiro gripped his wooden sword, mimicking Aoi's posture as he began to swing. Yuichiro followed suit with surprising focus. Though his movements were still stiff and unpracticed, he tried his best to adhere to Aoi's pointers, engaging his core and keeping his wrists locked. Even when his arms began to tremble with fatigue, he didn't stop.
Aoi moved between them. Noticing Muichiro's form slipping, she placed a steadying hand on his waist to guide his center of gravity. "Keep your back straight. Follow the flow of my strength. Yes, exactly like that."
The brothers listened intently, adjusting their movements bit by bit. The only sounds in the quiet courtyard were the rhythmic whoosh of wooden blades cutting through the air and Aoi's occasional soft corrections.
By the time they finished their hundredth swing, neither boy could lift his arms. Muichiro collapsed onto the porch steps, rubbing his sore shoulders with a little whimper. Yuichiro leaned against the doorframe, panting heavily, yet he refused to let go of his wooden sword, his knuckles white around the grip.
"If we master these techniques... will we be able to protect Mom and Dad?" Yuichiro asked, his gaze fixed on Aoi.
"Yes," Aoi nodded, her expression firm and certain. "Not only will you be able to protect your family, but you'll be able to protect yourselves—and anyone else you care about."
Yuichiro's grip tightened further. A look of determination, far beyond his years, flickered in his eyes. He looked up at Aoi, then stole a sideways glance at his exhausted younger brother.
"I'll practice until I'm the best," Yuichiro muttered. "I don't care how tired I get. From now on, I'll be the one to protect Mom and Dad, and Muichiro, and..."
He cut himself off abruptly, a sudden flush of crimson creeping up to the tips of his ears. He looked down quickly, staring at his reddened palms as the rest of the sentence died in his throat—And I'll protect you, too.
Aoi stepped forward and reached out, ruffling his messy hair with a warm smile. "I know you're both brave young men. But don't rush it. Take it one step at a time. Only with a solid foundation can you truly become strong."
As the sun began to dip below the horizon, a cool mountain breeze brushed against Aoi's face.
Since transmigrating into this world, Aoi had rarely felt this much peace. She brushed a stray lock of hair behind her ear and looked at the two boys sitting on the steps. "Yuichiro, Muichiro, do you want to play a game?"
At the word "game," both pairs of eyes lit up instantly.
Muichiro sat up straight, his mint-green eyes full of anticipation. "A game? What kind of game, Aoi-nee?"
Yuichiro looked over as well, though he tried to keep his voice level. "What is it? Better not be some childish nonsense."
Aoi suppressed a smile as she reached into her pocket, retrieving several sheets of bright, colorful paper she had just exchanged for in the System Space. "We're going to make paper airplanes."
"Paper... airplanes?" Muichiro tilted his head, reaching out to poke the colorful paper. His fingers brushed the smooth, glossy surface, and he looked up with pure curiosity. "Can this thin paper really fly?"
Yuichiro leaned in too, his brow furrowed as he inspected the paper. He couldn't help his stubborn streak: "It looks soft and flimsy. How can that be fun?"
Despite his words, he didn't move an inch. His eyes were glued to the vibrant colors, clearly intrigued. He had never seen anything like it; it was something entirely new and wondrous.
Aoi handed a sheet to each of them and kept one for herself. "Watch me. First, fold the paper in half... then fold the corners down like this to make a crease... and finally, fold the sides down to make the wings. There! A paper airplane."
Her fingers moved with practiced agility. Within moments, a sharp-nosed paper airplane appeared in her hand. With a gentle flick of her wrist into the evening breeze, the plane glided forward, soaring across the courtyard and landing softly near the vegetable patch.
"Whoa! It flew!" Muichiro cheered instantly. He grabbed his paper and crowded close to Aoi, his small shoulder bumping against her arm. "Aoi-nee, Aoi-nee! Teach me! I want to make one that flies that far!"
Yuichiro silently dragged a small stone over to sit on. He spread his paper out on the flat surface and began mimicking Aoi's movements, his fingers a bit clumsy but his expression incredibly focused.
A moment later, he had completed a plane with sharp, clean edges. It was slightly smaller than Aoi's, but perfectly symmetrical.
"Shall we see whose flies the farthest?" Aoi asked, her eyes crinkling with mischief.
"You're on! I'm definitely going to win!" Yuichiro challenged, his competitive spirit flaring up.
Laughter echoed through the yard, mingled with the soft rustle of paper catching the wind. Watching the brothers' smiles, a profound, unshakeable tenderness welled up in Aoi's heart.
A song drifted into her mind—one she hadn't thought of in a long time—and she found herself humming, then softly singing the lyrics:
"The order of our lives, beginning in the same glow,Existing in this world, the only 'only' I'll ever know.Every step in the future, every footprint we trace,We'll walk toward our dreams at each other's pace.Though the wind may blow and the rain may fall,I'll hold your hand tight and stand through it all.Every step in the future, every footprint we leave,To know, to cherish, to live, and believe!Don't forget the promise that we made back then,I'll be by your side, time and time again..."
"Aoi-nee, what are you singing?" Muichiro asked curiously.
"This song?" Aoi leaned down and gently patted Muichiro's head. "It's called 'Hand in Hand.' It's a song for the most precious people in your life. It's about the promise to walk together, to protect and stay by each other's side forever."
Muichiro blinked his large, watery eyes. "So it's a song for me and Brother, right?"
"That's right. Muichiro and Yuichiro are the most precious people to one another."
"Mm!"
The summer twilight lingered as the ink-black sky slowly unfurled. One by one, the stars began to peek through. Aoi pointed up toward the constellation of Gemini.
"Look there. That's called Gemini—the Twins. Just like Muichiro and Yuichiro, they stand side by side forever, protecting and lighting the way for each other."
Muichiro's eyes widened. "Gemini? Then Brother and I are the Gemini of the human world, right? Always together, practicing swords and making paper airplanes!"
"Yes," Aoi whispered, pulling both boys into a warm embrace. "The dearest 'Gemini' in the world."
The three of them sat together in silence, listening to the unique song of the summer cicadas. The evening breeze ruffled their hair, and the starlight seemed to pour down, wrapping their tiny corner of the world in a soft, eternal glow.