Byōki

Byōki is described as the most vicious cat poison curse used against Mao and Nanoka Kiba.

He speaks with the old-fashioned first-person pronoun equivalent of “this old one,” giving him an archaic and menacing air.

He is a tailed cat fiend whose tail has split into seven branches.

His motif comes from the Chinese monster Maogui, a cat spirit said to arise from poison-curse practices.

Byōki survives by taking over human bodies and continuing his existence through possession.

After consuming a secret manuscript from a treasure vault, he learned the Art of Taizan Fukun, a forbidden technique that allows him to manipulate human lifespan.

Byōki originally had a full body, but his current form is only a head from the neck up.

This happened when he tried to possess Mao and had his head severed.

Although his head was cut off, his body fused with Mao instead of dying completely.

Because that body remains merged with Mao, damaging Byōki’s severed head is not enough to destroy him.

He also suffered an injury to his left eye during a confrontation with Mao.

That wound became one of the visible marks of their long conflict.

Byōki’s core ability is body possession.

He can inhabit people and use them as vessels, allowing him to persist over long periods.

His most dangerous power is the lifespan-controlling art he gained from the forbidden Art of Taizan Fukun.

With it, he can alter the length of a person’s life, making him terrifying even without direct combat.

He is also tied to a curse so deep that Mao remains alive because of the cat spirit’s malediction.

For that reason, it is believed that killing Byōki would also take Mao’s life.

Byōki lay dormant for hundreds of years beneath a keystone under a church hidden inside a second barrier erected within the already sealed town of Five Elements Town.

He remained trapped there in concealment for ages.

The church’s barrier had been protected by flea-like spirits.

When those spirits were wiped out, the keystone became exposed.

Later, the Great Kanto Earthquake caused the keystone to disappear.

That event allowed Byōki to emerge onto the surface again.

After resurfacing, he confronted Mao and injured him in battle, while also taking damage to his own left eye.

Immediately afterward, he cursed the child Nanoka Kiba, who had been drawn into the Taisho era.

He then fled to the modern era.

His plan was to wait until Nanoka Kiba grew up and use her as a vessel.

To prepare for that future, he manipulated the lifespan of Nanoka Kiba’s Grandpa.

This shows how carefully and cruelly he plans across generations.

Byōki is one of the central reasons Mao and Nanoka Kiba are bound together by misfortune.

His curse reaches across time, linking the Taisho era and the present day.

His failed attempt to possess Mao permanently altered both of them.

Byōki lost his body, while Mao became entangled with the curse at a life-or-death level.

His curse on Nanoka Kiba was not random.

He specifically intended to let her mature into a suitable vessel for himself.

Byōki was long believed to be Graymaru, the pet cat of Sana, transformed into a monster through poison-curse rites.

However, the truth is stranger.

Rather than originally being an ordinary cat changed by poison rites, he was actually a yokai from the start.

He belonged to none of the five elemental phases or the dual forces of yin and yang.

Because of that, he could not be defeated with yin-yang techniques.

This made him uniquely valuable and dangerous.

According to the account in the source text, a master who wanted a feline yokai immune to yin-yang arts as a familiar made a wager, and a curse was placed at the Hall of Five Colors that prevented the parties involved from dying unless they killed one another.

This background reinforces Byōki’s deep ties to cursecraft, contracts, and unnatural survival.

Byōki is a character from Rumiko Takahashi’s manga MAO.

His voice actor is Takashi Matsuyama.

Within the story, he stands out as one of the most unsettling enemies because he combines possession, immortality-like persistence, and lifespan manipulation.

He is not just a beast to be fought, but a curse that keeps reaching into other people’s lives.

A related note from the source mentions that the shikigami Funa Uozumi regularly makes Nanoka Kiba drink homemade smoothies to protect her.

The smoothies are said to taste absolutely terrible.

The name Byōki is based on the Japanese rendering of Maogui, the notorious cat-based poison curse said to have spread widely in ancient China during the Sui dynasty.

The character’s concept directly draws from that tradition of feared cat spirits born from poison sorcery.

The source also distinguishes this figure from other uses of the same term, such as the general poison-curse spirit and unrelated folklore creatures from the Kamakura period and from Fukushima Prefecture.

In this entry, the term refers specifically to the MAO character.