[Diaper Use, Soiling, Farting, Brainwashing]

The dead of night had fallen on the Shinobi World. Most commoners were asleep, which left plenty of space for the Shinobi to move around and do the various tasks that they needed to pull off.

One of those Shinobi was the Gas-enthusiast Kuroudo, known for wielding bioweapons that most would consider absurd in the service of Good or Evil. But, she was the type that didn't care much for that conflict, so she kept on using them. Perfecting them. Developing them beyond their perfections until she had the most varied arsenal she could possibly wield.

It all came to a head today. Beneath her mask, she took a deep breath and tried to keep her footing. Her vision was getting quite hazy as she took every step, and every leap made her feel woozy. For good reason too, as she looked down. Bound by her black bodysuit was a rather large bulge that pushed out against the fabric, stemming from her belly. It wasn't quite solid, as every movement caused it to wobble and contract, which in turn caused a brief whistle sound to expunge itself from her bottom.

But she could handle it. She had trained for this, she just needed the perfect target to test everything out on. And as luck would have it, she had gathered just the right intel that would lead her to the victim of her new technique's test drive. She knew that the rogue shinobi from Hebijo lived in a forest nearby, so she just had to...

Kuroudo's eyes suddenly widened as she felt a presence, prompting her to jump further up into the trees to hide. Upon looking down and confirming her suspicious feeling, she could see a certain sandy-blonde girl dressed in such casual clothes, despite the cold weather that brushed against her exposed skin.

"Hooo... How strange, those goodie two-shoed Shinobi that tend to hang out around here haven't arrived yet. And here I was, looking for a few bodies to experiment on..." The girl, Haruka, sighed as she stretched a little. "I suppose Yomi might've taken them out on one of her patrols. She never was one for leaving a job half-finished, even if it could inconvenience one of us. Not that it matters that much, but it's still a pain!" She lamented her problem, laughing a little about it in the process.

There was her target. One of the Crimson Squad Shinobi that had split off and gone their own route in life. Just like Kuroudo had. Which meant that she would be the perfect target for her technique since nobody but the squad would care about the damage she'd do to the girl... and they were going to feel the brunt of the after-effects of the technique.

She pulled down her mask for a brief moment to take a deep breath, only to exhale a bit of the gas that she had pent up within her belly... "Now or never. Ninpo." The Gaseous Shinobi held a pair of fingers in front of her face as she jumped straight down, ass-first as she tried to land straight on the girl that had seemingly left herself completely open...

Or so she thought, as she was grabbed in mid-air by a mechanical-looking drone. "W-Wha? L-Let me go!" The purple-haired girl struggled against her captor, even as she made a fool of herself in the process with how her belly bounced all over the place, being practically flung from one side to the other from all the gas stored within.

"My my, what a forward approach. You're not one of the usual faces either. I'm glad I decided to bring my sweet little pet along, otherwise, you might've caught me off guard. And we can't have that, now can we?" Haruka licked her lips as she chimed, putting a hand on the unmasked Shinobi. "Although you're a bit ridiculous, aren't you? What kind of Shinobi would proudly display her bloated belly like that? Are you some sort of pervert, or is the Shinobi system so botched that they would train physically unfit students to wage war against one another?"

The target kept prattling on and on as the gas-filled Shinobi started to groan and rumble, the contents of her stomach threatening to blow out at any point. "Oh, I'm just rambling at this point, aren't I? You're not going to get any fun out of that belly while I'm around, that much I'm sure of. So, I think I'll just toss you to the side and let you blow up like one of those weapons you probably adore. A shame, since I know Mirai would love to study the techniques you use, but I simply cannot have a girl like you hanging around and stinking up our hideout. Homura would skin me alive."

A mechanical whirr resounded from the thing that held Kuroudo, as it pulled back its arm to prepare for the biggest throw it had ever attempted to perform...

"Tricked ya. Release..!"

The purple-haired Shinobi's arms were completely unattended, which meant that she could merely push down on her belly and release most of the gas that had been built up within her belly. In one explosive and messy burst from her plump rear, she released enough gas to knock out a fully grown adult man, the purple smoke quickly rushing into Haruka's lungs and temporarily incapacitating her despite her innate resistance through her training.

She immediately started gasping for fresh air as her connection to her robot faltered, causing it to release the purple-haired girl and allow her to stand right back up, with the tables now completely turned. Instead of the sadistic formerly Evil Shinobi having the upper hand, now it was the gas user's turn. And the grin on her face couldn't be wider as she started imagining all the things she could subject poor Haruka to...

"G-G... You're... Quite the clever girl, aren't you? What kind of disgusting creature would even try to use her own farts as a weapo-" The sandy-blonde tried to ask, only to cough up the farts that had rushed into her lungs, discoloring the air around her face in the process. Her eyes blurred for a second as she tried to focus on the girl that had turned the tables so thoroughly...

Only to see something overtly purple instead of a human's face. On closer inspection, this seemed to be a latex-covered diaper, designed to soak up as much gas as possible so that she wouldn't waste any of her own exhaust. Which meant... that most of the gas that hadn't been forced into Haruka's lungs were now being pumped straight back into the bloated girl's belly, to be reused in a few moments.

Kuroudo took this chance to push her padded butt straight up against Haruka's poor face, smashing her head into the ground and pinning her underneath that soft yet stretchy material. She could feel her stomach rumbling, begging for release. Her crotch wasn't far behind either as the front of her specialized underwear started growing rather wet and uncomfortable to touch. So, she did what she had intended from the start. The gas was merely a distraction.

A loud rumble and a groan left the gas-wielding Shinobi's lips as the girl she had pinned underneath started putting two and two together. If she had managed to stun her using her farts, then what would possibly happen if she was used as a makeshift toilet seat for an enormous diaper...?

"S-Stop! I beg you! You can't humiliate me like this!"

But she could. And she was going to. The formerly masked Shinobi bit into her lower lip as she pushed and pushed, both with her butt and with her hands, trying to force everything that had been building within her belly out the same way the stunning gas had. An obnoxiously loud and tuba-like brassy sound flew straight out of her covered hole, most of the gas rushing straight into the poor Shinobi's head and lungs to not only further stun her but also make her utterly unable to think straight... which made the next part work that much better.

The gas gave way to something much fouler, much more corruptive and much more ultimately damaging. An elongated and humongous snake of shit slipped it's way straight out of Kuroudo's anus, packing its way straight into the back of that enormous diaper causing it to sag downward in seconds. And with that sag, it completely encompassed the face of the girl she had been pinning, forcing the stench to soak in as much as it possibly could.

Of course, even as the energies within her shit started working their magic on Haruka, she continued pushing out more and more gas, with the occasional turd flying out of her widened hole in between just to make the load atop of her head that much more unbearable.

The gas inside of the sandy blonde's head was quickly eating away at anything sensible within her brain, turning what would normally be disgust at what was happening into nothing but pure bliss and adoration. Diapers were... shit was... farts were...!

It was all lovely! She wanted more! She needed more to live, but how!? Her eyes quickly turned the same shade of purple as the diaper as she started audibly huffing the gas and the scent of the freshly soiled diaper, as she started reaching down to her thighs to play with herself. She needed... she...

Haruka could feel her colon contracting as her brain understood exactly what she wanted. To mess herself, to join in and make as much of that disgusting stuff as the girl atop of her. She gasped and pushed, only for a pitiful snake to slither its way out of her plump cheeks. Unremarkable, but a good start. She just needed a little more...

"Haaah... You turned out... quite well..!"

Kuroudo's voice echoed from above as she smiled, pumping out one last rope of shit into her diaper before pulling herself straight off that intoxicated girl, a little bit of drool running down her chin as her belly had evened itself out. "Doesn't it feel nice, giving into stink... to Gas..?" She asked, giggling like a bit of a drunk ditz while stepping away from her victim...

The sandy blonde had to pause and question if it really did... only for her hand to preemptively push at the load in her panties, causing a shock to run through her system. "Y-yessss..." She muttered, blushing as she wanted more, weakly crawling towards the diaper-dumping Shinobi's bottom...

Only to be stopped by her foot as she gently pushed the needy girl away. "That's great because I've got something you can help me with. Something that'll let you have as much of your very own Gas as you'd like. And it comes with free stinkies too, so you can give into even more smells. What do you say, do you want that?"

Haruka immediately launched into puppy-like nods, eager and willing to give the rest of herself up to reach an even greater high. She then felt something spreading her thighs apart, and the lack of mess pushing up against her bottom.

Looking down, she noticed what had happened! She was now wearing a pink latex diaper, matching her usual Shinobi outfit while being the exact same size as Kuroudo's. It no doubt served the very same purpose too, as she gradually felt gas swelling up within her belly.

"Listen carefully, my new Gas Shinobi..." The purple-haired girl whispered as she slipped her mask back on, gently rubbing at the broken girl's belly and diaper to keep her in a state of pleasure. "All I need you to do is spread your gas to your friends. Make them diaper-loving gas addicts like us. Then report back to me here, in about a week. Then we can all make so many more gas Shinobi that the world has to notice the superiority of it. Sounds good, doesn't it?" With every word that bounced around in the sandy blonde's head, her new mistress rubbed into her sensitive spots that much more. Tying the sensation of obeying such dirty orders to pure pleasure...

Haruka drooled as her eyes started rolling into the back of her head slightly, panting audibly. "Make... Make everyone diaper-lovers with my gas... yesssss!" She cried out in ecstasy as she slowly staggered to her feet, kissing her Mistress on the cheek as her purple eyes turned to hearts. "I-I'll make Mistress proud, make a whole new Gas Squad for her! Just watch!"

With that, she took off. No need to wait when you had things to do... A mindset that Kuroudo agreed with, as she stretched slightly. She hadn't anticipated that her secret weapon would be this effective, but if it meant that she got new friends that loved the weird stuff she did... Well, it'd all be worth it.

She cracked a smile, and let a little more gas slip out of her hole before she disappeared into the night. Now, it was Haruka's turn to show her friends what she had experienced.