Ryu Hyesung is a high school senior with terrible grades, no clear future, and one overwhelming obsession: designing weapons.

To him, however, they are just toys.

A cheap drone that can fly autonomously. A homemade interception turret. A reusable rocket modeled after a multi-warhead missile. Hyesung builds whatever catches his imagination, caring more about whether it looks cool than whether anyone else thinks it is possible.

Then he decides to sell one of his creations online.

What begins as a way to fund his hobby quickly spirals beyond anything he could have imagined. Foreign buyers appear. Military researchers start asking questions. Intelligence agencies begin watching from the shadows. Governments across the world become convinced that a mysterious technological genius is secretly developing next-generation weapons.

Meanwhile, Hyesung is still falling asleep in class, worrying about his grades, and running a tiny toy company with his friends.

As every new “toy” creates an even greater international uproar, one question spreads among the world’s most powerful nations:

Who is Ryu Hyesung—and how can they get him on their side?

A fast-paced modern technology comedy filled with genius inventions, business growth, international misunderstandings, and an increasingly absurd arms race over a boy who only wanted enough money to keep building cool things.