Somewhere in the mountains of Seoul, where the sound of metal striking resonates loudly since morning, a young boy struggles to wake up.

"Damn, is it time to go to school already? Ah... I can't get used to this sound, no matter how often I hear it."

The boy's name is Lee Shin-hyeok, a 15-year-old second-year middle school student. Suddenly, his door bursts open.

"Brother! What time is it, and you're still sleeping? Everyone else is already up and doing their own thing! You can't even wake up, brother!"

His younger sister, Lee Shin-ju, a diligent 12-year-old fifth-grader, scolds him.

"Ah, okay, okay. Stop yelling! I'll get dressed and go out!"

After sending his sister away, Shin-hyeok gets dressed and heads out. As he leaves, he sees strong men hammering red-hot iron. He recognizes the familiar sight and greets them.

"Mister, you're working hard since morning."

"Kuhahaha, you bastard! This is our family business! And go to Shin-ju quickly, or you'll get scolded again!"

The sound of metal striking is the sound of swords being forged. Shin-hyeok's family has been crafting swords and practicing swordsmanship for generations. Their home, nestled in the mountains, resembles a small village with traditional tile-roofed houses.

Shin-hyeok heads to the innermost part of the house, where his father, Lee Kang-seok, and his sister, Shin-ju, are waiting. Shin-hyeok's mother passed away while giving birth to Shin-ju, so Shin-ju, who grew up quickly, always prepares breakfast for him.

Kang-seok, a skilled swordsman, is dissatisfied with Shin-hyeok's lack of dedication to training.

"Shin-hyeok. Are you training hard in swordsmanship these days?"

"...That..."

Kang-seok sighs. "Hmm... Come home right after school! I'll teach you today!"

Knowing his father's serious personality, Shin-hyeok gets up quickly, skipping breakfast.

"I'm going to school."

"Hey! Brother! If you made me food, I should've finished it! Why didn't you leave any?"

"Ah! I'll eat it when I get back. Put it in the fridge! I'm going!"

Shin-hyeok quickly leaves the house, wondering what his father will say.

Meanwhile, in Uruguay, an unidentified earthquake strikes. A flash of red light rises from the ground, followed by tremors. This strange phenomenon makes headlines worldwide, including in Korea. Lee Kang-seok, who happens to be watching TV, witnesses the news report.

Suddenly, a violent earthquake rocks Seoul! The ground cracks open, revealing a red light.

Shin-ju, who was at school, is evacuated due to the earthquake. Once it subsides, she returns home early for safety reasons. Shin-hyeok, knowing his father's expectations, decides to delay his return.

"Even if I go home, I'll keep training until my father likes it, so I should go right when school ends."

Shin-hyeok sits in the PC room with his friends, playing games and delaying his return home.

An hour into the game, a thought jolts him. "Shin-ju!" Her elementary school isn't far from his middle school. If he had gotten off school early, Shin-ju would have definitely gone home too.

Realizing this, Shin-hyeok jumps up and grabs his bag. "Hey, Deokbae! I'm going home!"

"Hey! Lee Shin-hyeok! We're playing a 2-on-2 game right now, what if I go now?"

"I don't know! If I don't go now, I'll be killed by dad! I'll see you at school tomorrow!"

Leaving his friends behind, Shin-hyeok sprints home at full speed.

Back at Shin-hyeok's house, Kang-seok senses something strange and gathers the people. The swordsmiths head to the blacksmith shop, while others assemble at the central training center.

"Is everyone okay?"

"Yes, I'm okay, Your Majesty!" Kang-seok, as the head of the family, ensures everyone's safety. He also encounters Shin-ju, who had returned home early.

"Shin-ju, didn't you see Shin-hyeok when you came home?"

"Um... Oppa, he'll probably be late?"

"What do you mean?"

"Well, if he comes home early, Dad will train Oppa in swordsmanship, so he'll be as late as possible. Hahaha."

Kang-seok nods, understanding his daughter's quick-wittedness.

Suddenly, an earthquake shakes the training grounds. Kang-seok grabs Shin-ju and tries to escape.

A chilling sound echoes through the air, a mix of animalistic and human cries. Kang-seok pauses, sensing danger.

Meanwhile, Shin-hyeok sprints towards home, fueled by the fear of his father's wrath.

As he approaches the house, a strange sight greets him. White smoke billows, and a red pillar of fire engulfs the training ground. Sensing something is amiss, Shin-hyeok discards his bag and rushes towards the fire.

The scene that unfolds is horrifying. His father, covered in blood, is fighting a monstrous creature. His sister, Shin-ju, lies unconscious on the ground.

"What the heck! What is that monster?!" Shin-hyeok yells, desperate to help.

Blacksmith Lee Do-jae tries to stop him. "Master, it's dangerous to go in now!"

"Let go of me! My father is in danger!"

"Trust the priest! Our Admiral Yi Sun-sin, the best swordsman..."

Before Do-jae can finish, Kang-seok is fatally wounded by the monster.

"Father!" Shin-hyeok screams in anguish.

The monster, now focused on Shin-hyeok, declares, "Where is Yi Sun-sin? I will kill Yi Sun-sin!"

A red light engulfs the training ground, and the monster melts away. The training ground collapses, burying Kang-seok and Shin-ju beneath the rubble.

Shin-hyeok's family members try to put out the fire, but it's too late. The fire consumes everything, leaving only ashes.

Overcome with grief, Shin-hyeok tries to dig through the rubble to find his loved ones. Do-jae tries to stop him, but Shin-hyeok is determined.

As he digs, he finds a sword. He picks it up, feeling a surge of power. Suddenly, Do-jae attacks, knocking Shin-hyeok unconscious.

When Shin-hyeok wakes up, he sees two coffins, holding the remains of his father and sister. The sight is too much for him to bear, and he collapses.

The next day, the funeral for Kang-seok and Shin-ju takes place. Shin-hyeok attends, his heart heavy with grief.

At the end of the funeral, Shin-hyeok throws his sword to the ground.

"What is the strongest swordsmanship? What is a proud family? Even my father, who was so strong, was defeated in an instant!"

He shouts with a grief, "Admiral Yi Sun-sin's swordsmanship is useless! Our ancestors passed down useless things to us! Very weak! Useless! Our Lee family, Chungmugong Seoul Branch, is disbanding today!"