Takeshi Onimaru - Yaiba

 

Takeshi Onimaru
Kanji/Katakana: 鬼丸猛 (おにまる たけし)
Race: Human, later Oni
Gender: Male
First Appearance: Chapter 4
Seiyuu:

• Ryo Horikawa (Yaiba anime, Detective Conan OVA)

• Kenjiro Tsuda (Detective Conan anime)

• Yoshimasa Hosoya (Yaiba anime remake)

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Character Overview
Takeshi Onimaru, the dark mirror to Yaiba’s fiery spirit, stands not only as a rival but as the looming shadow cast by ambition corrupted. Once a prodigy of discipline and steel, his soul was ensnared by the wind god’s whisper—the Fuujin Sword—and through its malevolent breath, he was reshaped into an Oni: a demon of might and fury. His fall from grace is not just a twist of fate but a tempest of power that consumed his humanity. Only when the winds of Yamata no Orochi calmed did the last remnants of Takeshi’s original self rise from the ashes of his demonic reign.

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Appearance
Before the darkness took him, Onimaru bore the face of a stern youth—tall, lean, and solemn as a temple bell. His scalp was unadorned by hair, as if to echo the clarity and emptiness he pursued through Kendo. Clad in the humble black uniform of a student, or at times the white-and-black garb of his dojo, he was the image of rigid resolve.

But once the Oni’s fire was lit within, his form became that of a warlord summoned from myth. His body grew thick with muscle and shadow, his brow crowned by wicked horns. In battle, he wore a baroque suit of armor as grim as it was glorious—shoulders bristling with spikes, limbs sheathed in fur-trimmed greaves, and a breastplate grinning with a death’s-head smile. Draped in crimson and sometimes bearing a dragon-helm, he cut a figure both regal and monstrous. Some tales even speak of a jetpack thrumming on his back, an unholy fusion of sorcery and science.

During the Oda Nobunaga tournament, he shed this infernal guise for a black kimono—simple, yet no less imposing, like a storm waiting to break.

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Personality
Takeshi Onimaru is a blade honed by silence, a man who walks the razor’s edge between discipline and wrath. Humor finds no foothold in him; mockery is met not with wit, but with vengeance. His fury simmers just beneath the surface—once, a jest from Yaiba was enough to provoke a midnight assault.

As an Oni, he becomes something far more terrible: a tyrant forged of fire and ambition. Power, not peace, is his creed. He rules with icy precision, valuing only loyalty and strength. Those who fail him—save for the brilliant minds like Professor Kanabo—are swept aside like ash in the wind. Yet, even in that darkness, a flicker of code remains: a warped, yet persistent sense of honor.

By the arc’s end, after the fall of Orochi and the guidance of Kenjuuro, the storm that was Takeshi begins to still. Hatred gives way to clarity. He no longer seeks domination, but redemption—a warrior no longer driven by vengeance, but peace.

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Abilities
Even before the demon’s touch, Onimaru’s blade sang truer than most. He once felled the mighty Kumazawa with a single strike—a whisper of death. But when the Oni awakened within him, so too did powers born of nightmares: dark sorcery, the command of infernal entities like the Black Oni, and the sway of hypnotic spells. His fusion of martial mastery and malevolent magic made him not just a threat, but a legend.

Weapons

• Fuujin Sword (風神剣 Fuujin Ken) The sword of Fuujin, the God of Wind (also referred to as "The Devil of Wind), an ancient heirloom of the Onimaru family, kept in a dungeon under Onimaru's home. It has a long, single-edged blade with an oval, oblong guard and striped handle. There's a blue orb in the middle of the hilt. There's also a secret writing on the blade which can only be seen under moonlight. Thanks to this sword, Takeshi merged with Fuujin and became a Oni. He kept the blade as his weapon of choice during most of the series, and even though it was snapped in half during the Onimaru's Fortress Arc it was repaired. He eventually gave the sword to Yaiba during the Kaguya arc.

• Devil King Sword (魔王剣 Maoken) The Devil King Sword is a fiendish weapon of incredible power forged by Kaguya and is the evil counterpart of the Supreme King Sword. It looks like a huge, double-edged longsword with a black blade and white borders. The handle is black and rectangular, and with a white tip. The hilt itself is composed by a round body shaped like a fiendish head (with the open mouth serving as a power gauge) and two horn-shaped arms protunding to the sides and adorned by what seems to be black fur. The blade of the weapon is slightly larger at the bottom and sports a hook near the hilt. This blade can turn the evil spirit of the user into energy blasts capable of erasing all life from the Earth. When fully unleashed the blade turns into black energy. This weapon is originally wielded by Gekko.

• Fuurai Bazooka A bazooka that utilizes full powers of the Raijin Orb and Fuujin Orb to release a massive and destructive energy blast capable of destroying a planet.
  

Techniques

• Fuujin Ha (風神波 Wind God Wave) First used by Onimaru to defeat Yaiba on the school grounds, consist in a blast of wind shot from the sword's tip. It was named during the battle against Yaiba at the fortress.
• Wind Blade: A variation of the Fuujin Ha and Onimaru's most common attack: a crescent shaped bullet of air capable of slashing through buildings.
• Sorcery: Thanks to his status as a Oni, Onimaru can now use magic and sorcery, usually to turn helpless animals into humanoid demons to do his bidding.
• Summon Black Oni: By throwing a handful of spikes and making a spell gesture, Onimaru can summon several Black Oni from the ground to act as his minions. He can seemingly summon an infinite number of servants this way.
• Necromancy: Using spells similar to the ones used to create the demons, Onimaru can bring back to life ancient warriors and give them a beast-like body along with the possibility of taking human form.
• Hypnosis: Thanks to his demonic powers, Onimaru can brainwash people with a glare. He first used this power to put the Japanese government in the Diet Palace under his control.
• Tatsumaki Giri: (竜巻斬り Tornado Slash) Onimaru's trump card, developed under Kanabo's advice. Onimaru extends the arm holding the sword of Fuujin and spins on himself as he release more and more energy, creating a huge tornado which he then throws at his enemy like a drilling beam of energy. When first used was powerful enough to perforate Mount Fuji and rise as far as space.
• Furaijinha (風雷神波 Thunder-Wind Gods Wave) A powerful combined attack powerful enough to pierce through a whole galaxy, it requires the combined energy of both the Raijin and Fujin Orbs to work. It was first used by Yaiba and Onimaru to defeat Gekko.
• Yoko Ichimonji: A iaido technique which delivers and incredibly fast slash at the enemy with razor-sharp air, aimed at a vital spot. Onimaru first used this technique while fighting Yaiba on the Yamata no Orochi.
• Tojin (闘刃 Battle Sword): An illusionary technique, in which the user summons his fighting spirit in the form of a flurry of invisible but discernable blades which distracts the enemy.