The plot revolves around the ownership of Gensokyo's land disappearing after the opening of the markets. To add on to that, an invasion from the Animal Realm has begun. Various characters go out to either halt the invasion or to take advantage of the situation.
Has been convinced that she's the second coming of the legendary monkey, Sun Wukong.
It was assumed that all the ownership of Gensokyo's land had gone up in smoke, but there was actually one region that authority-holding spirits still had on lock.
Namely, the Yamanba's sanctuary land.
An untouchable sanctuary in the Youkai Mountain's foothills.
While the phantoms that owned that land were going back and forth on whether they should give up the ownership rights, she came along, ate them, and transformed into an oni. She awakened as an oni while still having her physical body.
At this rate, she would certainly fall into Hell, and be met with awful torment.
Then Yachie Kicchou made contact with her, under the pretense of preventing her from falling to Hell.
But in reality, she was used as a foothold for the Kiketsu Family's above-ground advance.
Yet her introduction to Yachie, and the circumstances that led her to eat the phantoms, were both Zanmu's doing.
Was it Sun Wukong who was dancing atop her palm, or the beasts?
Saki is hyping her up as being "just like Cerberus itself".
A yamainu who once ate Zanmu's flesh back when Zanmu was human.
As a result, she is eternally cursed.
She lived quietly in the Forest of Magic, but she never fully awakened despite having a close-to-eternal lifespan.
She spent a long time as a simple beast who was getting on in years, idly waiting for the flame of her life to expire.
But one day, something called to her from the depths of her heart.
It was the voice of the strange monk, who had kept laughing even though Enoko ate her flesh.
"Lucky beast, who devoured mine flesh. A beautiful gem lies nearby. Devour it."
In response to that voice that made her heart tremble, her latent power awakened.
The gemstone was similar to one of the Moon's precious orbs, which purified life.
The moment the beast picked it up, all the impurity around her began to be siphoned away.
It seemed that she had become truly immortal.
The voice continued, giving her orders. "Devour all the beast spirits up here atop the land."
However, the strongest beast spirit of all, Saki Kurokoma, met and placated her.
The one who introduced Saki to her... was also that strange monk, Zanmu.
By the way, her bear trap opens when she splays her hand, and snaps shut when she clenches her fist. It's very dangerou... um, convenient.
A cursed youkai whose true form is unknown, wreathed in fire and blood.
Her true form is said to be a mujina, but everyone who's seen her says they can't imagine that's the case.
Surface-dwelling humans fear her because she is said to be a chupacabra, but she doesn't like being thought of as a monster with such a weird name.
She's a weirdo who feels perfectly comfortable in the Former Hell of Blood Pools.
She settled down in the Former Hell of Blood Pools before Toutetsu arrived there.
She lives off of sucking creatures' blood, but wasn't satisfied with lukewarm living blood, so she arrived at the Former Hell of Blood Pools in search of cursed blood writhing with resentment.
Since the Former Hell of Blood Pools was so perfectly suited to her, she's already lost all interest in the surface world.
Since she already lived in Hell and ate the modern Blood Pools' leftovers, the Former Hell of Blood Pools was paradise for her.
Very recently, she was informed of Toutetsu's presence by Zanmu, an old acquaintance of hers.
She and Toutetsu were very much alike, and they hit it off immediately.
According to Toutetsu, the beast spirits were currently fighting over territory in the surface world.
She had no interest in the surface's land-theft war, but as she saw Toutetsu looking forward to it, her blood started heating up.
She got an idea.
If she allied herself with Zanmu-- the one who'd cut off Former Hell-- she could get her hands on even stronger resentment.
A beautiful solicitor for Hell, who uses sweet words to drag anyone who carelessly approaches Hell down into it.
She tries to lure people into Hell with words, but if her target runs away, she'll chase them to the ends of the earth.
If you end up targeted by her, you're very likely to end up falling into Hell.
She apparently receives compensation for each soul she drags to Hell.
She promises that she'll share the compensation with dead souls, and thus lures them in.
And she apparently does share the compensation sometimes, so she's not disliked by humans who go to Hell.
Thanks to her, more spirits fall into Hell than otherwise planned, so the Yama is monitoring her.
She has a one-sided adoration for Zanmu, a strange monk who rules over Hell despite being human.
But she often gives excessive cooperation to her plans, to the point where it tends to get in the way.
She's one of the few individuals who doesn't behave according to Zanmu's predictions.
An oni who's reached the absolute pinnacle of eccentricity.
She was originally a corrupt monk who distanced herself from all the ways of this world.
She lived through the Sengoku period, and remembers all the cruelty and stubbornness of the world.
As a monk, she was forbidden from killing, but sensed a strong disconnect between that and the Sengoku-era culture in which one boasted about the number of heads one had killed.
She thought that if they were spirits instead of physical bodies, it'd count as salvation instead of slaughter, and started absorbing phantoms and beast spirits.
She also absorbed some beast-youkai spirits, thus discarding her life as a human, but she was wise enough to venture into Hell herself before she fell into it.
After falling to Hell, her unparalleled abilities and mesmerizing eloquence gained her the trust of the oni.
She herself had transformed into an oni already, but perhaps that only helped things along.
In contrast to most haughty and overpowering oni, she became an intelligentsia oni who ruled over Hell via dialogue.
She was also the one who proposed that they separate Former Hell, given its age and how paralyzed its functions were, and create a new Hell.
As a result, there's nobody in Former Hell who doesn't know Zanmu's name.
While it may be possible to control unintelligent evildoers with just an overpowering attitude, evildoers with cunning take more finesse.
She was very good at pacifying them at such times.
Modern Hell functioned very well as a safety net for evildoers, and it had her fine sense of balance to thank for that.
Now, several hundred years later, the Animal Realm's beast spirits have set their sights on taking over the surface world.
And then-- whether by coincidence or by necessity-- a particular event returned the surface land's ownership rights to nothing.
It'd only be a matter of time until the beasts got wind of this, and began to march up to the surface.
The Hell oni who saw this as a threat began to consolidate their forces, as if getting ready to wage war at any moment.
If a war between oni and beasts occurred on the surface, it'd quite literally be Hell on Earth.
Zanmu remembered the era of warring states. Gensokyo surely had no need for such cruelty.
She submitted a request for the oni to wait, in exchange for her taking care of the situation.
Then, from behind the scenes, she goaded each beast spirit leader into deploying their troops at the same time.
Her plan was to put the groups into a three-way deadlock, have them divide and conquer, and ultimately claim them all for herself.
She was well aware of each beast's thoughts.
It was simple to make them act exactly as she wished.
But she didn't know that there was a human in Gensokyo who'd gathered support from the youkai.
That certainly changed things.
There was no reason to give it to those measly beasts.
She'd leave Gensokyo in the hands of that human.
That human not unlike herself, who had gathered support from all the oni and beasts.