[Sumo TF, Weight Gain, Reality Change, Futanari]

"Well well, looks like you decided to come after all. I'm glad that you all received my invite."

"Of course we would. You're inviting us to stop you from causing an incident. It's my duty as the Hakurei Shrine Maiden to stop these incidents. Not just for the sake of the peace of Gensokyo, but because you'll just keep giving me headaches if I don't."

"Hehehe, Reimu might only be doing this because she really wants to relax, but I'm more than ready for a good show, da ze!"

"I'm honored that you would send me a direct challenge as well, but make no mistake. The Moriya Shrine Maiden is even more fearsome than the Hakurei Shrine Maiden! You will bow before the power of a god!"

Standing on two edges of an elaborate arena were four different girls. Four different individuals that had once faced off against one another during the fallout of the Mausoleum incident. A tricky Bake-danuki, and the three Humans that were willing to stop her from whatever she might be scheming.

Futatsuiwa Mamizou. A tricky woman who could imitate anybody should she get the chance to assume their form. But unlike every other time she had confronted these heroines, this time she wasn't wearing any of her disguises, nor had she taken upon a form that would let her overpower them by tricking their minds. She just stood there at the edge of the arena, grinning with her arms crossed and her kiseru carefully balanced on her lip.

The three heroines that would stand tall and fight back against whatever she had planned were Hakurei Reimu, Kirisame Marisa and Kochiya Sanae. All three were experienced incident solvers and certified Youkai Busters. With the power of the danmaku at their disposal, they would be a difficult opponent for Mamizou to overpower all by her lonesome. Especially now that she had practically outed herself as the main cause of a brand new incident.

Mamizou grabbed her kiseru, before twirling it around and turning it into a simple leaf. "Let me ask this of you. Did you all read your invitation properly?" She asked, all while her grin started to widen ever slightly while she climbed onto the raised stage in front of her...

Reimu raised an eyebrow. She hadn't, though judging by the gleeful grins on both Marisa and Sanae's faces, it seemed like they had actually bothered reading the full thing. "O-Of course we have." She stuttered and let a blatant lie slip forth, all while keeping a close eye on Mamizou. What was she trying to accomplish with this arena...

"Then you must understand exactly what this incident will be all about." Mamizou said, as she grabbed ahold of her clothes. Firmly wrapping her fingers around the fabric, all while her grin twisted and grew as sharp as it could. "The Yokozuna stakes her claim on this holy land!"

With her voice echoing out through the air, Mamizou ripped her outfit apart. Leaving her naked for but a split second, as one of her leaves slowly started to drift to the ground. And in the process, her body slowly started to smoke. Thick smoke billowing forth from her form...

All three heroines watched as Mamizou's form very quickly started to balloon outward. Every single part of her body grew nice and thick, whether it was her arms, her legs, her neck, her fingers... Inches upon inches of fat were layering outward until it looked like she was practically immobile. And that was just her limbs...

If you looked at her torso, something that was practically impossible to avoid, you'd see her stomach pushing out further and further. Inch after inch, foot after foot. While her body had grown nice and thick and excessive, that paled in comparison to her main girth. Her heavenly girth, which just kept on stretching until it looked like gravity would start weighing it down. And yet there was no sight of it affecting her. Even as the fat poured out to the sides, making her torso look more naturally balanced to go with the belly, she still didn't falter under her own weight.

Not even her breasts growing to the point where both of them were the size of beanbags, Mamizou did not falter. If anything, the fact that she had unleashed everything just filled her body with more vigor. Especially as she slowly started to lift her leg up into the air, tilting until her foot pointed straight into the air... And then she slammed it back down, letting the stage underneath quake in the face of her true might...

Standing upon that stage, now having revealed her true size to the three heroines that would try to stop her, Mamizou laughed in the face of their impending challenge. "This is the incident you'll be facing, girls! The mighty Yokozuna, Futatsuiwa Mamizou!" She cried out, all while running her fat fingers along the sides of the massive rope that was wrapped around her waist. The same rope that had a cloth attached at the front, obscuring anything between her thighs. "Will you meet my challenge, or will you become my concubines? Come, step forth!"

Reimu didn't exactly know what she should be feeling at this point. Disgust was definitely a valid emotion, especially as she kept looking at that enormous belly and how Mamizou's hair seemed to have been done in that traditional sumo wrestler style. Beyond disgust, another bout of confusion filled her heart. How in the world had she been able to disguise that much weight? And could she even really pose as a threat to the three of them, now that she had-

"Master Spark!"

Her question was rather abruptly answered as Marisa whipped out her hakkero, blasting a beam of pure magic energy straight at Mamizou's gut. Or rather, she would've, if not for the fact that there was a powerful barrier situated right around the stage itself, preventing the energy from forcing its way inside and leaving the Ordinary Magician's attack rather worthless.

"A barrier of that caliber... That's power beyond the work of gods!" Sanae cried out, glaring towards the Bane-Danuki that had made her intentions clear. "So you wish for us to fight you on your playing field. Only a coward fights on their terms!" She was furious. Especially because she had just thought up a brand new spell card that would've let her harness even greater power.

Mamizou laughed in the face of her complaints. "The Yokozuna makes the rules. Climb onto the stage and fight me like you mean it, that's the only way you'll be able to stop me." She explained, still grinning despite her advanced size and the fact that she should be caving in on herself with that much fat on her body...

Reimu narrowed her eyes. Something about this wasn't right. It shouldn't be possible for Mamizou to pull off stunts like these. But at the same time, she didn't think that it was necessary to whip out her true power just yet. She'd just have to observe. Because she already knew that those two were going to go on ahead and accept the challenge and all that it entailed, regardless of the consequences.

Indeed, both Marisa and Sanae grabbed ahold of the edge of the stage and pulled themselves up, Marisa even rolling stylishly into the main part of the ring that had been drawn on the stage. All while grabbing ahold of her own clothes...

"You want a fight, huh, Yokozuna? Then I'll give you a fight!" Marisa cried out with vigor as she ripped off her clothes. But instead of her meager and petite form being shown off to the world, her body just erupted into fat, not unlike what had happened to Mamizou. The main difference being in the sheer layers of fat.

While Mamizou was beyond fat, Marisa's new form was just a smidge obese. Her stomach was pushing out as if she was pregnant with twins for a few weeks after they were supposed to pop out, while her limbs were not yet thick enough to the point where the fat was sagging. And yet that didn't stop her arms from looking like oversized tubes, just like her legs were looking extra stiff due to all the space taken up by her flabby body...

And yet despite the fact that her body had been changed in the blink of an eye, Marisa didn't seem to be deterred. In fact, she barely even noticed a difference. She lifted her leg, just as Mamizou had done, before slamming it down and letting the Mawashi that dug into her waist and her pussy squeeze tighter... "Come on, Yokozuna! I'm ready to take you on!" She cried out, slamming a hand against her fat belly and letting the waves ripple across that mass, all while grinning in the face of the much larger enemy.

Sanae took a deep breath as she managed to climb onto the stage. While she was able to control the wind and use it in danmaku combat, that didn't mean she was especially athletic or anything. But even so, she stood tall and grabbed ahold of her own outfit once faced with the Yokozuna. "You'll understand how wrong you were to challenge one of the Gods, Yokozuna!"

Her outfit was torn off just like theirs were, revealing her extremely fat body hidden underneath. And while Marisa's fat was best described as a firm apple in how it was mostly concentrated on her belly, especially with how firm that very same fat was, Sanae's was sagging beyond belief. To the point where you could barely even see the green Mawashi wrapped around her waist.

Not that you'd be looking down there, nor at the thick limbs that made her look nearly immobile. No, what your eyes gravitated towards was either the fat belly that looked even bigger than Marisa's, complete with sagging and drooping downward as it pushed further outward, or her head-smashing tits. Those massive melons were made for destruction, to the point where anybody that hadn't been felled by her belly would be completely destroyed once those colossal mounds smashed against the sides of their head...

Okay. Now Reimu definitely knew part of what was going on. The barrier was not only there to protect Mamizou from external attacks, but it was clear that if you were to enter it, you would end up another fatty with a sumo obsession. That was easy enough for her to tell. The question then became 'what would happen if they were to lose?'

It was a question that she would receive a quick answer to, as both of the heroines that had been converted to sumos quickly dashed forward, grabbing ahold of the massive rope that was wrapped around the Yokozuna's waist. All while digging their heels into the ground to make sure that they put as much power into their shoves as possible.

And yet nothing happened. Mamizou just kept her arms crossed, pressing them up against her mammary mountains. All while laughing at their pitiful attempts to dethrone her. Though she had to admit that it did tickle. That's all that their struggle amounted to. Nothing more than a slight tickle against her heavy body.

"If you wish to best me, then you better put in more effort than that!" Mamizou cried out as she let her arms rest, right as a glint appeared in her eyes and she slammed her hands forward. "DOSUKOI!" She shouted, signifying that she had begun her offensive.

Neither Marisa nor Sanae were prepared, as both felt that massive hand slam straight into their guts. It was enough to make them winded, and it was enough to knock them over while pushing them towards the edge of the ring. Not that they ended up falling off the stage, the barrier ensured that they wouldn't meet harm in such a way. But there was still no way around it, they had both lost in such a humiliating fashion...

"Stand tall, concubines!" Mamizou shouted, power pouring through her voice as it started making the stage underneath her glow. "You've lost your match against the Yokozuna, so you both understand what that means!" Oh yes. She loved this part. This was the part that honestly made her start this entire incident in the first place, and why she had gone directly towards the three heroines that could possibly stop her.

Marisa and Sanae slowly got back up, their eyes having turned a deep shade of brown as they started slapping their bellies like they were drums. To herald in the Yokozuna's victory, their eyes spinning as they started giggling and drooling. They could feel it all slowly just pour through her...

Before a burst of cum splashed through their Mawashi, announcing their orgasm in the process. "We swear to be the Yokozuna's loyal and adoring sumo concubines! That is our sole purpose in this life! To serve her and make her happy, no matter what she might want from us!" They both cried out, gasping and panting. All while they squatted down and pressed their hands behind their head. "Breed us if you so desire, o Yokozuna! Our bellies and all of our holes are yours and yours alone!"

Reimu had seen enough, her body turning intangible as she flew onto the stage. "Alright, I'm not letting another second of this pass. You've gone far enough, twisting them into forms that don't fit them." Using her power to Fly, she was going to bypass the barrier and all of this. Because there was no way that she was going to end up a sumo like them! "Say your prayers, Mamizou. I'm going to exterminate this part of you and turn you back into the thin and conniving Bake-Danuki that you've always been!"

Mamizou merely grinned, all while Reimu landed in front of her. "Do you truly believe that you can best me, Reimu? Your friends have fallen, what makes you believe that you'll be able to do what they could not?" She was as smug as before. Especially as the cloth in front of her groin started to tent at the sight of such an eager and strong challenger...

"I can beat you. There's no way that I'd lose to a false Yokozuna like you!" Reimu cried out as she tore her own outfit off, barely even aware that anything changed. Despite the fact that there was now a very powerful rope wrapped around her belly, and her belly was pushing out far further than it ever had before, and the fact that her limbs were now way thicker than her head.

But no, it wasn't the fact that Reimu had suddenly gained just like the other sumo that made her stake the claim as Yokozuna. No, the reason why she had done so came in the form of the massive shaft between her legs, the enormous rod that tented the cloth in front of her crotch while also revealing the equally ginormous set of seed tanks that were hanging between those thighs. That was her pride as a Yokozuna. The thing that would allow her to beat Mamizou.

"Face me with all of your might, you fake Yokozuna!" Reimu cried out, as she pressed her gut right up against Mamizou's. She was still far thinner than the Bake-Danuki, but at least she was able to push her back ever slightly. Which was more than could be said in regards to her friends' efforts, considering how they were completely and utterly unable to do anything.

Mamizou laughed in response to how she was being pushed back. "A fellow Yokozuna. But you know that there can only be one true Yokozuna, Reimu!" The excessively heavy Bake-Danuki cried out, all while her own cloth started to tent. Letting her own member reveal itself, and quickly show that it was much thicker and much larger than the one that the Shrine Maiden was equipped with. "The heaviest, the most virile, and the strongest Yokozuna is the true one! DOSUKOI!"

Reimu didn't get a chance to defend. There was no way that she could defend. The moment that she managed to catch a whiff of Mamizou's scent spelled the end for her fight against her. That massive belly slammed straight into her and knocked her onto her back, forcing her cock to squirt in response. Raining down cum onto her belly, signaling her complete and utter defeat at the hands of a superior wrestler...

"Stand, concubine!" Mamizou's voice echoed out. "Cast aside your role as a fake Yokozuna and submit! Offer yourself to the one that has bested you, and be prepared for a life of nothing but pleasure for the sake of the one that owns you!" Her voice was booming. Her voice was commanding. But most importantly, it was completely and utterly impossible for a defeated sumo to fight back against.

Reimu let out pitiful cries of pleasure, all while her cock started to shrink. Even her rope turned into an ordinary Mawashi, as she lost all claim to the title of Yokozuna. And in the process, her very self was twisted. Because she didn't need to be anything except for a concubine. The only thing she needed to be was ready for her Yokozuna...

The Shrine Maiden of Paradise slowly got up onto her feet, despite how heavy she had grown, and grabbed ahold of her flab before spreading it as much as she could. All to expose her quivering and needy navel. "Yes..! I've lost..! And I submit to you, my Yokozuna! Make me yours, breed me as much as you'd like! Do anything you want to be, I'm yours and yours alone!" Her eyes had turned the same shade of brown as the others, showing her complete and utter devotion. Especially as her reformed pussy drooled like mad at the sight of the cock between her Yokozuna's legs...

Mamizou stepped forward, as her cock drooled in anticipation. With these three heroines as part of her harem, there was nothing that was going to be able to stop her. Once she had impregnated them and made sure they couldn't change back, then the rest of Gensokyo would fall as well.

It would no longer be a world of fantasy. No, it would be a world of Sumo, and a world subjugated by her weight...