Humiya slowly ascended the slopes of the Hira Mountains north of Kyoto. Hir heavy layers of fat made the going slow, but the tanuki's muscles were more than up to the task. Shi was in search of a witch who could transform Kijo and Misaki into shiyūdōtai, as well as turn the human Misaki into a yokai. The mountains were your best bet for finding a witch of you weren't lucky enough to have one set up a workshop in your town. They allowed witches to be close to the nature they drew their powers from, and their rugged terrain gave them many places to hide their secret arts from prying mortal eyes.
After a few hours of searching, Humiya spotted a mountain cave with oddly colored smoke pouring from its entrance. Few caves emitted green smoke if a witch DIDN'T live in them, Humiya figured. Shi stepped through the mouth of the cave to investigate.
The interior of the cave was strewn with strange pots and animal bones. In the middle was a smoking and bubbling pot over a fire. A woman hunched over the pot, naked aside from a noh mask depicting an oni. A snake, clearly a familiar, slithered down her arm. The woman turned to face Humiya. "Greetings, young tanuki. I am Saku. Welcome to my humble cave."
"Greetings, Saku-sama," Humiya said, bowing slightly. "I am Humiya Omoibushi. I am a senior student at Kyodainayokai-beya, Kyūri Sensei's sumo heya. I come to humbly beg you to use your spells on our behalf."
"What do you wish done?" asked Saku.
"We have two new female pupils," said Humiya, "an oni named Kijo and a human named Misaki. It is forbidden to teach sumo to women, so my sensei and I wish for you to turn them into shiyūdōtai. Misaki's humanity must also be cast aside. She has entered the world of the yokai, so she must become a yokai herself. She personally wishes to be a kitsune, if you could manage that."
The masked witch thought about it. "Those are not simple spells. They will test the limits of my magic, so what would you be willing to offer me in return?"
"What would you ask of me?" Humiya asked.
"I think I have an idea," said Saku. "Tanuki semen is a very potent spell ingredient. I think I'll even need it for the futanari potion you want for your new classmates. If you allow me to milk you for some, I will help you and that crusty old kappa."
"Good thing I'm single right now," Saku chuckled. "Deal!"
Saku lay down on the cave floor and spread her legs. Humiya dropped hir loincloth and stroked hir cock to an erection. The tanuki knelt over Saku, positioned hir cock over the witch's entrance, and shoved it in. Humiya pistoned hir dick inside Saku, hir enormous, cushiony belly rubbing against the witch's thin body as shi did. Going by her blissful sighs, Saku seemed to be enjoying the feel of fur over fat rubbing over her.
"I take it my belly isn't in the way, Saku-sama?" Humiya smiled.
"On the contrary," said Saku, "It's arousing me further."
Humiya kept up hir energetic fucking, hir colossal, oversized balls slapping hard against Saku's thighs as shi did. All the while, Saku's snake familiar kept a careful watch over the two as they entwined. After a few more glorious minutes of hammering Saku's cunt, Humiya felt hir climax starting to build. "I... I th-think I'm ready to release, Saku-sama!"
"Draw out, then," Saku instructed. "It will all be wasted if you just squirt it all inside me!"
Humiya did as shi was told and pulled out of Saku. Saku grabbed a wooden bowl. Humiya aimed hir cock straight at the bowl as the first of hir load blew, a long strand of sticky cum landing on the bowl's center. Another gooey rope followed, and then another. Soon, the bowl was filled to the brim with precious tanuki cum. The exhausted tanuki slumped to the ground.
Saku stared greedily at the bowl, her eyes (the only part of her face visible behind her strange mask) lighting up. "Semen from our nation's most phallic of species! Many spells depend on its presence. Yes, Humiya, I will grant your request. Kijo and Misaki shall be changed."