kokkotsu No Yaiba
KOKKOTSU NO YAIBA
The Blade of Bone
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SYNOPSIS
In the 10th century of the Falce Era, the world was small. Thatched huts, herbal medicine, fragile lives.
Until the Nula Virus arrived.
Herbivorous animals turned into bloodthirsty monsters. Wild boars, deer, elk—everything that once lived on leaves began to live on flesh and bone. Their bodies grew up to five meters tall. Wounds healed on their own. No human weapon could stop them.
Humans called these creatures Ghuldemon.
They discovered their weakness: sunlight would immobilize them for two hours. They discovered their only vulnerability: only Ghuldemon bones could pierce their hearts, covered in layers of diamond-hard bone.
And they discovered something more. When a human wielded these bones, they gained elemental power—fire, water, earth, wind, light, darkness—which fused with their own blood, giving rise to clans of hunters with unique abilities.
But the true terror was yet to come.
Miraí Youtaka, a hunter like many others, was bitten by a rare Ghuldemon. She didn’t die. She transformed.
The first Ycan. Immortal. Devourer of humans. Queen of the night.
In a single night, she slaughtered her own village. Devoured her family. And from her back, four tentacles were born that would never stop killing.
Now, five hundred years later, the war between humans and Ycan has no end.
Raya Otakata is a fourteen-year-old boy living in a small village with his family. His eyes are special—he can see ten times better than any human. But that doesn’t matter when you can’t walk, can’t speak, can’t even hold a sword.
Raya has always been this way. A prison of flesh and bone since birth.
Until one night, a Ycan invaded his home.
His family was massacred. Raya survived by chance—and when he woke up, his body was healed. Whole. For the first time in fourteen years, he could move, run, fight.
Now, carrying only a golden earring left behind by the killer, Raya seeks revenge. But the path is long. The exam to become a Ycan hunter is deadly—four trials that few survive.
And on the horizon, Queen Miraí is still searching for something. A descendant. An heir. A "future king" who could shift the balance of the world.
Meanwhile, on the other side of the region, Kurai Sengoku—the only friend Raya ever had—has also joined the exam. Separated by fate, each walks their own path of pain, loss, and growth.
Because the world of the Ycan does not wait. And the night... the night never ends.
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ELEMENTS OF THE WORK
Element | Description
Genre | Dark fantasy, action, horror, drama
Setting | Taicho Era (15th century) — Feudal Japan with fantasy elements
Protagonists | Raya (revenge, special eyes, dark energy) and Kurai (loyalty, strategy, growth)
Antagonists | Miraí (Ycan Queen, seeking an heir), Ryusei (3rd Archon, cold and elegant)
Human power system | Ryokioko Tensei (Flow of the Sun) — 7 primary styles, including the extremely rare Dark style
Ycan power system | Gyōketsu (Blood Techniques) — unique abilities based on past life
Weapons | Ghulcam (forged from Ghuldemon bones) → evolves into Mitsurikage (the hunter’s unique weapon)
Ycan hierarchy | Queen (Miraí) → Pillars (5, full tongue marks) → Archons (divided marks) → Common Ycan
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HUNTER EXAMS (THE FOUR TRIALS)
Trial | Description
1st — The Open Wound | Night hunt against a Ycan. Borrowed Ghulcam may fail.
2nd — The Dead Smith’s Trial | Find an unfinished weapon and complete it by killing a Ycan.
3rd — The Blood Tournament | Combat against other candidates. Tests pressure and strategy.
4th — The Midnight Ritual | Face your own shadow in an ancient cemetery. The Ghulcam becomes a Mitsurikage.
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HIGHLIGHTED QUOTES
"The world doesn’t ask for permission. It only takes."
"If you’re not ready to lose... go back home."
"A Ghulcam answers to no one but its owner."
"Even clouds have bad days. They cry when it rains. When the pain is too much... they scream. Man called it lightning."
"The night still belongs to the Ycan. And the