Transported to an unfamiliar era, everything felt strangely out of place.
At five years old, when he first arrived, Kaigaku knew only his name and nothing else. Orphaned, he wandered the streets, scraping by, sometimes fed, often starving—a pitiful existence.
Yet, Kaigaku's soul carried the spark of a future mind. With cunning and unyielding resolve, he survived the neon-lit Meiji era of Japan.
As he grew, he dreamed of leveraging his modern knowledge to rise to wealth and prominence. But reality struck hard at sixteen. One night, working late for extra coin, he met a ghost—a real one. A cannibalistic demon, grotesque with blue fangs, prowling the dark, craving human flesh and blood.
Cornered by the beast, Kaigaku's soul nearly fled in terror. Is this it? A time-traveler, undone before achieving greatness? Despair gripped him.
But fate intervened. As the demon lunged, a spirited old man descended, wielding a katana aglow with lightning. With one stroke, he beheaded the monster, reducing it to ash. Kaigaku, frozen on the ground, gaped at the old man, wreathed in faint electric sparks, his mind reeling.
Demons? Lightning warriors? This was no ordinary world. It clicked: Demon Slayer. Kaigaku had crossed into the world of Demon Slayer—and worse, he was its most irredeemable traitor.
In the original tale, Kaigaku, an orphan surviving on muddy water and theft, grew selfish and cruel. Taken in by Gyomei Himejima, he stole from the temple and was cast out. That night, encountering a demon, he betrayed the temple, extinguishing its wisteria incense to let the demon slaughter the children. Only four-year-old Sayo survived, and Gyomei fought to protect her, landing unjustly in prison.
Later, apprenticed to Jigoro Kuwajima to learn Thunder Breathing, Kaigaku's envy and cruelty persisted. He bullied his junior, Zenitsu Agatsuma, and alienated his comrades in the Demon Slayer Corps. When faced with the Upper Rank One, Kokushibo, he groveled, drank demon blood, and betrayed humanity. His actions drove Jigoro to seppuku in shame. In the final battle, Zenitsu slew the arrogant Kaigaku, ending his vile life.
Kaigaku was a villain beyond redemption, destined for infamy. Despair surged—Must I live this cursed life?
No. He refused. I'm here to rewrite this fate. Rising, he faced the old man, his white hair and prosthetic leg unmistakable: Jigoro Kuwajima, former Thunder Hashira, now a Demon Slayer trainer. A lifeline.
Throwing aside pride, Kaigaku bowed deeply. "Thank you for saving me, sir!"
Jigoro, struck by the boy's resolute gaze, felt a connection. "What's your name, lad?"
Kaigaku hesitated. Kaigaku—a name tied to cunning and treachery. He rejected it. "I'm Horitake," he declared firmly. "That's my name."
"Horitake? A fine name." Jigoro's eyes gleamed with approval. "Boy, would you train under me? Learn my skills?"
Horitake's heart leaped. "Yes! Master!" he replied, voice brimming with resolve.
Jigoro, touched, let petals of joy seem to swirl around him. Then, sobering, he warned, "My teachings are tough, and they come with great responsibility."
Horitake's gaze didn't waver. "I'm ready. You're a Demon Slayer, aren't you? I'll learn to slay demons and protect humanity!"
Jigoro's laughter boomed, his hand ruffling Horigaku's hair. "Good lad! I'll teach you everything—make you the greatest Demon Slayer!"
Horitake, overwhelmed by Jigoro's warmth, chuckled wryly. "Master, I get it, but please—my hair's a mess now."
"What's a little mess?" Jigoro grinned, unreserved.
"Master, some dignity, please!" Horitake teased.
Thus, the once-lonely Horitake was taken in by Jigoro Kuwajima. In the secluded Peach Mountain, he thrived under his master's care, soaking up knowledge with a sharp mind and honing his body with remarkable talent. Step by step, he mastered Thunder Breathing, determined to forge a new destiny.