Teitan Elementary, Grade 1–B.
Homeroom teacher Kobayashi Sumiko brought Watanabe Tetsu into the classroom.
She clapped her hands to gather the students' attention.
"Class, we have a new friend joining us today. You must not bully him—make sure to get along well, okay?"
Then she turned to Watanabe with a gentle smile.
"Alright, Watanabe-kun, please introduce yourself to everyone."
Watanabe gave a soft sigh, stepped onto the podium, and said,
"Hello everyone, I'm Watanabe Tetsu. Nice to meet you."
"Watanabe-kun will be part of our class from now on. Please help him with anything he's unfamiliar with. Now… Watanabe-kun, sit in the empty seat next to Yoshida-san."
Kobayashi arranged his seat.
"Yes." Watanabe nodded and walked to the desk.
As soon as he sat down, a delicate bell-like voice came from beside him.
"Hello, Watanabe-kun. I'm Yoshida Ayumi. Nice to meet you."
Watanabe glanced at the little girl and nodded slightly.
"Hello, Yoshida-san."
"If there's anything you need help with, you can always ask me," Ayumi said, full of senior-classmate responsibility.
"Thank you." Watanabe returned a smile.
"Hey, new guy."
Behind Ayumi, Genta poked out half his body—dark-skinned, sturdier than kids his age, and even when he tried to whisper, his voice buzzed like a motor.
"If anyone dares bully you, just say you're friends with me, Kojima Genta."
…Wow. Is your reputation really that big in this school?
Watanabe had just opened his mouth to respond when a stern voice came from the front:
"Kojima-kun, one more word and you'll be standing in the hallway."
Genta shrank instantly and fell silent.
The curriculum in Japanese elementary schools typically included national language, math, social studies, arts and crafts, music, PE, and home economics.
Besides being homeroom teacher, Kobayashi also taught Japanese and math.
A gentle breeze blew outside; birds chirped; warm sunlight shimmered across the big south-facing windows like golden powder.
In the classroom, after writing a math problem on the board, Kobayashi turned to the students.
"I'd like someone to solve this problem. Anyone want to volunteer?"
Silence. Some students even ducked their heads guiltily.
Kobayashi sighed lightly. She wasn't sure whether it was fear of her or the difficulty of the question. Her eyes swept across the room and—of course—stopped on today's transfer student.
"Watanabe-kun, would you like to give it a try?"
"Eh? Me?" Watanabe hadn't expected to be called on the first period of his first day. He paused, then stood up. "Yes."
"Poor guy… First day and he's already become Kobayashi-sensei's target…"
He faintly heard Genta's sympathetic whisper.
[Move one matchstick to make 8121 + 9 = 2]
Seeing the puzzle on the board, Watanabe felt his IQ had been insulted.
But after thinking a moment, he conceded that for ordinary first graders this indeed counted as a brain-buster.
Watanabe remained still for a few seconds. Kobayashi assumed he was stumped.
"This problem may be too difficult for everyone, so—"
She suddenly froze.
Because Watanabe picked up the chalk and wrote:
2 = 6 + 12 − 16
He—he actually solved it?
Kobayashi stared wide-eyed at Watanabe, who calmly set the chalk down. Her mouth hung open like she'd been hit by a paralyzing spell.
This problem was well beyond elementary level—many middle-schoolers couldn't solve it.
It tested not only reverse thinking, but also logical reasoning.
And who would've guessed that the key was to read the equation upside down?
But this transfer student had done exactly that.
"Sensei? …Sensei?"
The voice reaching her ears pulled Kobayashi out of her shock.
"Ah?"
"Sensei, did I get the problem right?"
"You solved it beautifully. But Watanabe-kun, could you share how you figured it out?"
"Of course."
After briefly explaining the reasoning, Watanabe returned to his seat.
As soon as he sat down, Ayumi leaned close with sparkling eyes.
"Watanabe-kun, you're amazing!"
Watanabe gave a small smile.
"Thank you."