[Fusion, Gas, Ass Focus, Musk, Futanari]

"Oh, Elder Sister... Oh, Elder Sister..!"

"Hm? Nobukatsu? What's the matter? Did Nobunaga turn you down again? Or is she off playing with Okita and you're jealous?"

"Ah, Master. You cut at my heart so easily. Y-yes, that's exactly the problem. Despite the fact that we were both summoned to Chaldea, despite the fact we're finally together on the same side after so long, she doesn't even take a moment to look at me. It really... Oh, Elder Sister..."

It was a rather pitiful sight. The Archer-class Servant, Oda Nobukatsu, had an undying love dedicated to his elder sister, Oda Nobunaga. He had been lucky enough to arrive in Chaldea after helping out Humanity several times throughout their journeys and adventures with her sister, but at this point it seemed like she was content to just ignore him. Did he truly matter this little to her?

His Master rubbed his cheek a bit, sighing. "You really love her that much, don't you, Nobukatsu?" The black-haired boy said with a soft smile on his face. He really did pity him. Because they were in the same boat. Nobunaga had been one of the first Servants to heed his call, and at this point she had decided to ignore him in favor of spending much more time with that Saberface. Why they got along so well was a mystery to him.

Nobukatsu nodded wildly as he buried his head in his knees. "If only she would just look towards me. It wouldn't take much more than that. I just want to see her smiling at me. Telling me how she wants to use me. Telling me that I'll be useful for her plans. Anything to have her acknowledge my presence. Ahhh, Elder Sister..." It was truly hopeless. He was practically incapacitated by the love he held for his Elder Sister. If somebody didn't try to fix his issues, he would be utterly useless and unable to do much of anything because he would just keep on simping for his own flesh and blood. Even if he himself thought that he wasn't worthy.

His Master smiled. As that grin on his face started to turn a bit too lewd. "Say, Nobukatsu." He said, his voice starting to turn a bit more sensual. "What if I told you that there's a way we can make her look at both of us?"

Nobukatsu blinked a few times as he listened, pulling his head up from his knees as he looked towards the boy that had summoned him. Only to flinch and nearly scream out in shock at what he saw.

His Master's body now more looked like a tight set of skin being pushed out, especially around the chest, while his face had been harmlessly torn off to reveal a darker-skinned feminine face underneath. W-What? Was his Master always like this? Had he always been like this and he just didn't notice because he wasn't paying attention? He didn't know what to do when faced with this information, besides feel a tinge of worry inside his heart.

"Let's start over from the beginning." The darker-skinned true form of the boy's Master said, clearing their throat as they brushed a hand through their rather puffy and extremely fluffy brown hair. How they had been able to keep that much hair stuffed into that... s-suit? Was a bit difficult to properly understand. "My name is Blair. Nobukatsu, you and I both love Nobunaga more than you'd like to believe. So, instead of worrying about how we'll get her attention individually, why don't we become one? Just do what I tell you, and we'll be with her. At all times."

Nobukatsu still didn't understand. He barely even understood that the person in front of him was still supposed to be the Master that had summoned him. But the seals on the back of their mismatched hand, since that part of the 'suit' hadn't yet been torn, made it clear that they were definitely still his Master. And as such...

HIs eyes lit up as he bowed down in front of his darker-skinned Master. "Anything! I'll do anything to make sure we're together with Elder Sister! Please, please tell me how!" He cried out, the desire to be with her welling up from within the depths of his heart...

Blair laughed. If there was anything that they had learned from having Nobukatsu by their side throughout their adventures with Nobunaga, it was that he was incredibly devoted as long as it involved his sister in some fashion. "Alright. Get up on your feet and take my hands. Then just take a deep breath." They gave him a simple order to follow. Even somebody like him, consumed by his own need to simp, couldn't mess that up.

Nobukatsu quickly nodded as he got up and weaved his fingers in between hers. Smiling as he felt his heart beating against his chest. He couldn't keep himself from vibrating. He was going to be with his beloved Elder Sister. How would he keep himself calm in this situation? There was absolutely no way-

His eyes very momentarily flashed red, and he noticed one of the seals disappearing on his Master's hand. All while his body started to feel weaker and weaker. Was he... He was using his Noble Phantasm, wasn't he? T-That would kill... No. Not like this it wouldn't. The smile on their face made it clear that there was something he hadn't picked up on, something that he only now understood.

Nobukatsu smiled as his body turned into little more than ashes. All while taking his Master with him, his Noble Phantasm consuming the two of them. Leaving little behind except the pile resting on the floor, a pile of indiscriminate ash...

Which quickly reformed, using the darker-skinned Master as the base. Blair gasping the second he managed to breathe once again, all while quickly looking at his body to make sure that everything had gone as he had planned. And it seemed like it had, because of the new sense of strength within him...

Not that it was actually new. The memories of his Saint Graph were shifting. As far as Bl... Nobukatsu understood, his body had always had a rather modest looking bosom, always had this darker shade of skin, always had this beautiful mane of brown hair that was all-too-puffy like an afro, and looked damn good in a sleeveless uniform and disgustingly tight shorts that snapped tightly around his cock. Yeah. That was who Nobukatsu was. Even if he wasn't quite aware of the fact that his Saint Graph had been contaminated by his old Master's essence.

For now, he had a lot more confidence in his body. And with his heart beating against his chest, he headed straight for his Elder Sister's room. All so he could tell her how much that he loved her, and how much he wanted her to spoil him.

All while the back of his hand started glowing, his Command Seals more than ready to help her understand...

---

There were very few things that were able to surprise Nobunaga, especially the Avenger-class version, ever since she arrived in Chaldea. Most of those things came as a result of the various adventures she went on together with Okita. But seeing somebody dressed as a much hornier version of her younger brother? Yeah, that was definitely able to make her raise an eyebrow.

"And who're you supposed to be?" The Demon King asked as she sat up, glaring towards the darker-skinned Nobukatsu-copycat. As far as she understood, that boy was little more than an imposter. "Better have a good answer. I'm not in a good mood." She said, on the verge of drawing her blade.

She didn't get that far. Not before her eyes started to flash nice and bright red thanks to the three seals that suddenly vanished from the darker-skinned boy's hand. Not before she noticed that rather needy grin on that bo- Nobukatsu's face. Of course, how could she have been so blind? That was her brother, through and through. That pitiful pervert who couldn't keep himself from getting close to her. Heh, maybe it was time to test and see if he could handle all of her.

Nobukatsu smiled as he stepped inside, giggling a little. Aaah, he had managed to use his Command Seals in quick succession. He'd probably see quick results too, because the changes that he had used them for weren't too dramatic-

*BRAAAAAAP*

The darker-skinned boy let out a gasp as it felt like his nostrils suddenly caught fire. All because of that disgustingly thick fart that his Elder Sister just ripped straight from her ass. There was absolutely no warning, absolutely no shame, and it was so strong that it forced him to collapse right onto his knees. Even though it hadn't even really reached his face yet.

"What's the matter, Nobukatsu?" Nobunaga laughed as she stood up and got closer to him. "Can't handle the heat? I thought you said you'd stick close to me no matter what. I thought you'd be able to handle me at my worst. But you can't handle a little gas?" She mocked him, but the tone of her voice made it clear that it wasn't out of hatred. It was because she knew that he loved it. "Here. Let's try and build up your resistance. Don't pass out too quick!"

Before he had the chance to try and stop her, even if he wasn't actually going to, the darker-skinned boy had his hair blown back by the force of his Elder Sister's farts. Those incredibly heated farts that were causing part of the floor to scorch, and a couple of tiny flames to flicker at the very ends of his puffy hair. Ah, it felt so good to be forced to inhale those farts. It felt like his lungs were catching on fire as he did so, but it made his body tremble and his cock try to cum straight through his incredibly tight shorts in the process. He wanted more. So much more.

*BRAAAAAAP*

And she was more than happy to give him exactly what she wanted. Very nearly forcing him up against that hole, letting him inhale every little speck of her flaming gas. The scorching fumes of hell itself. She was the Demon King, after all. Having her farts be comparable to the fumes of hell was something that only made sense.

"Hahahaha! Good to see you're enjoying it, Nobukatsu!" Nobunaga shouted as she watched her brother tremble and gasp and moan and pant like he always did whenever he was completely and utterly obsessed with her. But she felt that she could go further. She felt that she still had more to milk from him...

Which was when her body started to tremble. Her attire quickly shifted from the usual uniform that she wore as part of her existence as the Demon King, to the kind of attire that she wore when she was still on the rise. The attire that one of the other versions of herself wore whenever he managed to claw his way to the forefront, as evident by the way her hair suddenly tied into one long pony tail as her breasts compressed and her laughter gave way to a more masculine sounding voice.

Nobukatsu, whose eyes were currently stuck in a haze thanks to the fumes of hell still pouring through his head, gasped and panted as he looked up at his Elder... Brother. Yeah, that's what he currently was. And even though he was younger like this, even though he was definitely male, that didn't stop him from obsessing over him. In fact, seeing him like this was enough to make his cock throb even harder within his pants.

"Feels good to push that stinky bitch out of the way!" Nobunaga laughed as he looked down at his younger brother. "Then again, you're probably into that, aren't you, 'Katsu?" His much rougher way of speaking really contrasted his other self, especially as he firmly grasped his ass. An ass that was a lot bigger than it ever had been. "But don't you worry. I've got something much better than those farts you've been huffing. You ready, 'Katsu?"

Nobukatsu didn't really get the chance to dwell on what he was being offered before it was too late. He was forced straight onto the ground courtesy of that phenomenal ass hanging off his Elder Brother, that incredibly sweaty and incredibly large mound pressing up against him from both sides. It was impossible for him to break free from this incredible softness. Nor did he want to. To be sat on by his Elder Brother was something that he had always wanted. Especially if he was technically older than said Elder Brother whenever he was like this!

"C'mon, 'Katsu! Moan, scream out how much you like this! It's not every day you to be a throne for the future King!" Nobunaga laughed as he rocked his hips back and forth, causing him to grind that ass back and forth in the process. "Scream! I wanna hear it pour out from your lips! How much you want my ass!"

Nobukatsu couldn't exactly scream while he had his face buried in this much wonderful meat. While his normal Elder Sister's ass was something beautiful and something that could kill him if he ended up exposed to too much of her powerful fumes, this ass was divine in its own right. If he just kept on worshipping it, he was sure that he'd end up cumming before his Elder Brother even did anything. That was the kind of pull that ass had over him.

A moan barely managed to leave that crevice between the two meaty mountains, causing Nobunaga to laugh as he heard that pitiful sound. His laughter only grew louder as he heard the sound of his brother's cock squirting out more of that sticky seed that he had been trying to hold back. He truly was pitiful. But that was why he loved his little brother. It was why he was the very best to tease and bully!

Just as he was about to really rub that ass in, his body started trembling again, prompting the male Nobunaga to let out a dissatisfied groan as his body quickly started to expand upward and outward. A certain older version of both him and his female self had managed to take the reins.

Evident by the way that his body was quickly being covered in a very slim looking black bodysuit, his hips widening while his chest pushed out further than before. Two mature mounds kept nice and firm thanks to the aforementioned bodysuit, all while his hair was once again unbound as it turned as red as the blood that had been shed for his cause...

Or well, her cause. The true Demon King had manifested, as she lifted herself off her younger brother's body and looked down at him with the single eye that was left uncovered by her hair. Just looking down at him was bringing back memories of how much he craved her...

"Stand, Nobukatsu. I'll reward that devotion. Just this once."

Nobukatsu quickly panted and gasped as he got onto his knees and looked up at his Elder Sister, only to lock eyes on something big that was kept pinned within that bodysuit. Or at least, it was supposed to be kept pinned. But it was incredibly erect and it was forcibly stretching out the suit as it pointed straight at his face.

That wasn't the only thing about this older Nobunaga that was off, or the only thing that made him quiver. Every little part of her seemed to be significantly lacking in personal care. The sweat pouring down her body, the noticable stains on every little part of that bodysuit. She hadn't showered, much less cared to dive into any body of water in weeks. All because she didn't think she needed it.

Her musk was more powerful than anything else. It was a stench beyond belief, a stench that made her the true Demon King. A stench that was only emphasized by the sheer thickness of the musk pouring from her cock. It was the kind of stench that completely subjugated anybody that smelled it. And that was no less true for Nobukatsu...

Nobukatsu trembled as he got a whiff of both her odor and her musk. And his eyes almost immediately rolled into the back of his head. Not only was that cock so much bigger than his own, but it was so pungent that it forced him to cum in an instant. All while his body continued to tremble all over and his pants grew wetter and wetter as he had two orgasms back to back... No, not just two. The more he smelled her musk, the more it filled his brain and ate away at his mind, the more he just kept on cumming.

"Good, Nobukatsu. Good..." The true Demon King mused, all while she dragged a finger along the length of her cock. If nothing else, she could rely on him getting hooked on her cock. Then she could ram that rod straight into his hole and finally get some damned relief. And if he was good, he'd clean up the stain of cum on her bodysuit after she finished using him. Then she could conitnue using him as much as she'd like.

At least, that's what she would've done. If not for the way that her mind started to shift around. Within a few seconds, her body rapidly shifted between the three versions of herself. The younger female Demon King, the Male who had not yet achieved the title, and the older who was at her peak. The gassy one, the fat-assed one, and the one with the all-devouring odor.

Nobukatsu watched his Elder Sister swap back and forth rapidly, trembling as the kinks that he had imparted on them kept on switching. That wonderful gas, that divine ass and that hellish odor. It was all what he had wanted. All possible thanks to the fusion with his Master, not that he knew that had happened.

For now, the dark-skinned simp just sat there with his pants full of cum, ready for his Elder Sister to bully yet again. With her fumes, with his ass or with her cock!