How much explanation do you need on this one really? Also, feel free to consult my profile for the difference between a D-girl, herm, and a futa. Yes, there is a difference.
Saitama woke up in her bed with a yawn. Next to her were her two 'pets'. She'd had them since first deciding to become a hero three years ago. She woke the first of them, a red shelled anthro crab creature. She was human from the waist down, but covered in crab armor with claws on the top half of her body. She woke Crabrante with a hard smack to her rump.
She woke with a soft groan, and sat up in bed. "Morning Crabby~" Saitama said with a smile. Crabrante smiled back, moving down without needing to be told and moving the blankets, freeing the dick girl's solid, sixteen inch cock. She moved her head to it and began to lick along its length to lubricate it for her and the other pet. Saitama sighed happily, glad she didn't need to even order them. They'd both been broken long ago.
As Crabrante climbed up to straddle Saitama, she thought back to how she'd first gotten the crab girl all to herself. She'd just been leaving another job that had fired her shortly after discovering her alt. gender. One downside of living on a supercontinent, prejudices could encompass the entire world. It would be another full year before the hero's association formed and judgements like that went out the window as more and more futa, herm, and C-boy heroes started showing up and saving the day.
As she walked, she'd been confronted by Crabrante, back then a cruel, brutal monster with intent to kill and or rape anyone who got in her way. And judging from the look of her and the trail behind her, she'd done a pretty good job of doing so already. She'd threatened Saitama with rape, and when that didn't work, with death. Saitama was in too poor a mood to give a shit what happened to her, and upon seeing this, Crabrante let her go, not caring to bother with her.
Saitama went on her way, hoping maybe she could find another job in town that wouldn't throw her out immediately when she'd found Crabrante again, with a young boy. Saitama wasn't sure if the crab woman had been planning on killing him, raping him, or both, but she couldn't let either one happen, it just wasn't right. One brutal beating into the dirt later, Saitama found something burning in her, an odd mix of combative and lustful determination.
As the boy fled, Saitama pounced, enduring Crabrante's attacks and rough, aggressive sex. Eventually, she'd been able to turn the tables on her, pinning her down on her back and slamming her massive length into her hard. It took hours of rough, painful fucking, but by the end of it, Saitama had fucked her into a stupor that she never really came back from. Fucked silly Saitama believed the term was. Whatever it was, Crabrante hadn't left Saitama's size willingly since.
And now here she was, bouncing up and down on the D-girl's morning wood to please them both. She moaned happily, reaching up and groping Crabrante's ass as she rode her hard cock. Her legs were locked underneath her waist so she could pull herself down harder and hopefully even make it all the way to the base without blacking out immediately. If Saitama help still the entire time, perhaps she could.
She'd trained so hard after that day, both in fighting and in sex, that now she could defeat anyone sexually in a single thrust regardless of who or what they were. A single fucking would completely mind break them. Another example of this was her other pet, who'd just woken up. His name had been Dark Fish, but Saitama just called him Fishy because Dark Fish sounded too much like an edge lord name for her.
Fishy had woken and moved around, lowering his head to lick and suck on Saitama's balls while Crabrante rode her. Saitama moaned, smacking Fishy's ass hard. He moaned around her balls, sucking harder and wiggling his hips for another. She'd found him about a year into her training. She'd been looking for bad guys to fuck and/or fuck up for their bounty so she wouldn't be kicked out of her apartment. She'd stumbled across Fishy back when he was still a human.
Crabrante was human before too at some point, and Saitama wasn't really sure what made humans change into the monsters, but she didn't really care. All she needed to know is that it gave them powers and made them evil. In one shift, Fishy had gone from a human crime boss to a mutated fish person spewing acid and trying to kill her with a flog.
Saitama had quickly figured out that Fishy enjoyed being on either end of the flog. That, combined with a quick, rough fucking, had let her break and keep him for herself. She'd fought and fucked other monsters and even human villains since then, but hadn't really wanted to keep any of them. She heard about heroes getting full harems of defeated monsters and villains, and wondered if she should start making one of her own.
She grunted, cumming into Crabrante. She hadn't quite gotten to the base, but already cum once herself, cumming again now as she took the cum. She climbed off, panting a Fishy moved up to clean her rob. Saitama clicked the TV remote and turned on the TV, her mind still on possible harem building. As Fishy cleaned her, she watched the news reporting an attack from a tall, purple skinned dragon level monster. She'd already taken out two A class heroes, and they were calling on any and every hero in the area to help out.
Saitama pushed Fishy's head down, her rod pushing into his throat again as she came once more before getting up, deciding that she could take care of this one. Maybe take this Vaccine Woman as another harem member.
As you may have been able to tell, not all the characters will be changed by gender. Genos, for example, I plan to leave male unless you vote against it in the reviews. Puri-Puri may have to be changed to female, and a few others, but let me know in the reviews what characters you want gender bent and which ones you want left alone.
Also, for those who read this idea back when it was apart of Sinful's Drabbles, I wasn't sure how a female name for Saitama would work. The best I could come up with was Saitalla, which doesn't really sound right. Let me know in the reviews if you're fine with me just using the name Saitama, or if you have an idea for a more female sounding name.