[ABDL, Oni TF, Filth, Soiling]

Traversing through Time and fixing the issues that plagued Human History. That was the duty of Chaldea, the organization that stood at the very end of the near-incinerated present. No matter how difficult the task might seem, they were going to do everything in their power to make it right.

But that didn’t make it easy. Because for every problem they solved, another three cropped up. It was like dealing with a Hydra. Sure, they might get recognition and praise from the ones that lived in that era, but they would be just as forgotten as a result of the timestream patching itself together.

Not only that, but there were a few instances where they didn’t end up winning. And whenever they ended up on the back foot like this, they had to cut their losses and accept the ones they left behind. No matter what the situation was, no matter what had happened.

This was the case in one of the pockets of Japanese History. The Oni had been powered up to the point where they were easily able to overpower the humans, and their savior was nowhere to be found. Chaldea had to do everything to not only find the original version of the oni-slaying Minamoto no Raikou, but also repel the Oni. Otherwise, they wouldn’t be able to fix the timestream.

...But they failed. For two reasons. The first was the Oni horde being too powerful to overwhelm. Simply put, there were too many of them and they were way too strong, even for Servants with much superior weapons. The combination of reasonably high levels of power and numbers that weren’t to be messed with, resulted in a lot of them getting charged down. so the Master had to abandon the singularity and depart back for the present, leaving his Servants behind.

The other reason?

“Ara, Mama’s little Oni’s looking even prettier than the day before.”

The heroine that was supposed to save the humans had given into her oni instinct. And unlike the time where it had taken over her body during her later years, this time it took over and changed her from the inside out, twisting her into an oni until none of her humanity remained. All so she could spoil and dote on the ones that had fallen prey to her kin.

Raikou. The maternal woman that had done so much for her Master. Twisted into a chubby purple-skinned near-demon, with one massive addition around her waist. One that nearly sagged all the way down to the ground, with how much had been dumped into it. Oh yes. Not only had she been turned into a fat mockery of herself, but she was diapered and thoroughly messy as well…

She wasn’t the only one that had been twisted. In fact, she was personally responsible for quite a few twists herself. And the one she cared about more than any of the others, was the red-skinned baby girl laying on the floor in their little cozy hut.

“Mama!” The red-skinned Oni, formerly known as the proud Knight of Treachery Mordred, had been defeated by the purple-skinned maternal Oni. And the prize for her loss was a direct dump into that mess, twisting her from the outside in. Now, she remembered little of her time as a big girl. Or as a human, for that matter. All she now cared about was the love and affection of her big stinky mama!

Raikou giggled as she reached down and picked up her much smaller baby. “How’s my little Mo? Did you have fun with your siblings before they had to go hunt?” She asked, rubbing the girl’s cheek as she pushed her close to her chest. Oh, she loved the girl so much. Even if her mind was twisted into an exaggerated mockery of her existing issues, her love was genuine.

‘Mo’ nodded and drooled a little, the drool pouring down her mostly-naked body and down onto her dry diaper, soaking its way into the padding. “Mmhm! Big sissies went off to smash! And I nappied!” She giggled, her vocabulary having gone to the shitter since she was converted. Not that she cared. As long as her Mama understood her, it didn’t matter what words she used.

Her Mama nodded and kissed her on the cheek. “What a good little Oni Baby.” She giggled, as she carefully grabbed her waistband, the immense layers of pure filth ‘hidden’ within immediately letting their stench waft out. All while she lowered her towards it, feet already touch all that warm and mushy stuff.

The smaller Oni didn’t struggle against this. In fact, she almost tried to sink deeper on her own, liking the sensation of all that warm filth rubbing against her. It was really nice, just being this close to her Mama, and getting covered in a poopy blankie. It was something she had grown used to, ever since she was converted. In fact, this was how she was born! Inside this filth! So it was like returning to the womb, sorta, where she could shake around and get all sorts of nice and comfy and warm!

Once she saw that her dearest little Oni Baby was comfy, Raikou smiled from ear to ear. And then she squatted down, closing her eyes as she started to push. Because like any good Oni, she didn’t care when it was appropriate to take a fat shit. If she needed to, she was going to do it.

Fresh and warm filth flooded into her diaper, making it sink even further down as it all moved around. Some of the warmer stuff even moved to the front, letting the young Oni Baby get some more of it. Warming her, comforting her, heating her up and making her all fuzzy inside her tummy. Because she knew that her Mama cared so much about her.

Of course, this wasn’t entirely for her little Oni Baby’s benefit. Really, the purple-skinned Oni just needed to mess herself. It was the same way she had managed to incapacitate the girl in the past, defecating herself like wild without even considering what would happen to those around her. And it was the same way she had converted her. Stuffing her stunned form into the back of her diaper, and soiling all over her until she was turned into another Oni. The others met similar fates, but only her dearest Oni Baby went through this kind of rebirth.

Mo giggled as she played with the messy stuff, her skin staying a surprisingly clean red despite the massive filth around her. Because Oni didn’t need to clean themselves. Whether it was down below, or up above. Their skin couldn’t get dirty. No matter how hard they tried. And that meant that a filthy little Oni Baby like her could have as much fun with her Mama’s poopy as she wanted!

“Aaaahhh…” Raikou sighed as she finally stopped dumping out the contents of her bowels, sitting down and mushing her tush all around. Like the big messy Oni that she was, she loved feeling the sensation of her mess rub up against her. Because it wouldn’t smear off. She could enjoy this sensation as much as she’d like…

Her Oni Baby giggled as she mushed her away around, just like her big Mama did. She didn’t have a mess inside her diaper, but that didn’t stop her from trying to act like it. Besides, all the stinky stuff around her helped reinforce the ‘illusion’, so why shouldn’t she enjoy herself?

Both Mama and Baby laughed alongside one another as they enjoyed themselves, before the purple Oni slowly grabbed her child and turned her towards herself. Both had been having more than enough fun. But it was about time for them to have a bit to eat. While she was definitely hungry, her dearest Oni Baby’s tummy needed to be much more full than hers. She was a growing girl, after all.

Mo looked up at her Mama and the rather enormous breasts that hung off her chest. They were even bigger than when she was a human. And they needed to be that big. Otherwise, they couldn’t feed her dearest little Oni Baby. She needed as much of that milk as she could possibly stomach.

The blonde red-skinned Oni Baby grabbed ahold of one of those breasts that was twice as big as her head, before grabbing onto the nipple with her teeth as she started suckling from it. She could feel the incredibly thick milk rushing down her throat in an instant, her cheeks puffing out from just how much of it managed to stuff itself into her. And yet she kept on drinking and drinking, sparing nary a single moment to let it all pour down.

She was so thirsty. So hungry. She didn’t look like it or act like it, but an Oni, especially a Baby like her, needed so much nutrition to keep in tip-top shape that they often feasted an entire night, just to recover all the energy they spent throughout the day. And even though she barely spent any because she napped the entire time, she still loved to fill herself. In fact, there was another reason why she wanted to fill herself with her Mama’s milk, and it was a lot simpler than getting her tummy satiated.

Mo started to push as she swallowed more and more of that milk. To an Oni Baby, especially once as devoted and as growing as she was, milk like this would serve as a natural laxative. And if she wanted to be a real Oni, she needed to make messes that were just as big as Mama’s. And if that meant she had to drink lots and lots of milk, then she’d do it.

The more she drank, the more her Mama cried out in pleasure. Because being milked by her sweet little Baby was nothing more than the greatest high that a Mama like her could go through. And in tune with those cries, the Oni Baby’s tummy started to rumble. As if it wanted to push something out. And she pushed, to try and get it all out.

It seemed like it worked, as the pressure down below started to ease up. But the sweet and almost silent hiss from between her thighs made it clear that she hadn’t made a mess. Far from it. She had just peed herself. Just like every other day. Because she wasn’t a big Oni. So she couldn’t make her own messes…

Mo looked almost distraught as she kept on drinking, her diaper quickly filling with plenty of pee as it soaked it all up. She didn’t want it to be a mess made of peepee, she wanted to make it out of poopoo! And she’d drink as much as she could from Mama’s boobie until she made a messy!

Unfortunately, Mama didn’t let her go that far. Raikou quietly pulled her off her breast after her tummy started growing just as fat as Mama’s, the older and bigger Oni teasing her about it by squshing the milk-filled bulge on the girl’s tummy.

That very same squish was enough to make it all pour out, causing the poor Oni Baby to fill her pampers with as much pee as she possibly could, pushing her out of the mess in the process and lifting her closer to her Mama’s face.

“No fair! Wanna messy! Mama, how do I make messy?!” Mo cried out, nearly throwing a temper tantrum as she squished her way around inside her extremely soaked diaper, huffing and puffing like the baby that she was.

All that it earned her was a kiss on her lips, and a hug from Mama. “Ssssh. It’s okay, little Mo. You’ll make your own messies sooner or later. Mama promise.” She said, slowly rocking the girl back and forth…

Mo’s eyes fluttered as the warmth and the squishy nature of her Mama’s body made it hard to stay awake. Or angry for that matter, as she let out a cute burp and fell asleep in her arms. Forgetting everything about her little tantrum, and drifting off to dreamland like a good little Oni Baby.

Raikou giggled as she kept her baby in her arms, humming a soft tune as the two stayed together like this. Because despite how she had been changed, her maternal nature was still as pure as ever. Even when exaggerated.

...Eventually, Chaldea would find a way to rescue the two. But their bond would remain. A little Oni Baby, and her humongous Oni Mama...