Highschool DxD: Katerea's Sisters (Patreon)

“Damn it’s not enough,” Issei said to himself. He had been training for days but he has yet to make that much progress. The Topu Kaidan was approaching, and he knew that his current strength wasn’t enough to protect Rias. He was willing to do whatever it took to become stronger.

“You’re still too weak,” Ddraig said to his host. “You won’t stand a chance against anyone in your current state.

"Shut up! Don’t you think I know that!?” Issei yelled at Ddraig. “There has to be a way for me to get stronger faster!”

“There isn’t so train!” Ddraig yelled at him, trying to pump his owner up. Though part of the reason that he was yelling at Issei was thanks to him, Ddraig The Red Dragon was now known as the Oppai Dragon! He would let Issei use his full power unless it was a life-or-death scenario.

“Hahhh!” Issei yelled smashing a giant boulder in front of him with ease. Though when he did it was revealed that there was a magical circle right underneath his feet. Before he could do anything, Issei and Ddraig were teleported away. Seconds later they appeared in a fancy demon noble’ bedroom.

“Ddraig, what happened?” Issei asked, confused about how they were teleported so fast.

“It would appear that a high-ranked demon placed a trap for us, and we fell right into it. Based on the location of the circle it was probably placed days ago when we started training. They knew that we would eventually touch it and it would activate and bring us here. Though the real question is not the how but the why.”

“Why would they want to bring us here?” Issei asked Ddraig. “We were in the middle of nowhere and if they wanted to harm us why didn’t they just attack us there?”

“That’s because whoever they are didn’t want to harm you,” Sona Sitri, the student council president, said, walking up from behind Issei.

“Class Pres, what are you doing here?” Issei asked, shocked to see someone he knew there.

“I could be asking you the same thing, but I assume that you got caught by a teleportation circle as well.,” Sona said to him. “It would seem that whoever brought us here wanted the two of us personally. When I was teleported here, I was with some friends, but seeing how they’re not here means that they were either taken somewhere else or they weren’t teleported in the first place.”

“Tough that doesn’t matter,” Sona said to him. “What matters is that we figure out where we are and what we have to do to get out of here.”

“Fine then let’s get searching,” Issei said to her, walking over to the door, but it wouldn’t budge.

Sona and Issei spent the next several minutes trying to find a way out of the room, but every attempt they had, ended in failure. The room was sealed shut and it was impossible for either of them to use their magic and powers in this room. Whoever kidnapped them did not do so out of nowhere. This was planned for a long time.

“Urgh!” Issei grunted, trying to pull the door open again, but it wouldn’t budge for him. Though just as he was about to let go of it, the door swung open without warning!

“Wahhhh!” Issei yelled falling backward.

THUD!

“Hmm, it would seem the one chosen by Rias is quite the clumsy one~,” Katerea Leviathan, said, arrogantly entering the room.

“Wait you're-!”

“Yes, it is I Katerea Leviathan the true heir to the title of Maou Leviathan~,” she said looking down on Sona who was the sister of the current holder of the title she craved, Serafall.

“Why have you brought us here!?” Sona yelled at Katerea, knowing all the things that this woman has tried doing to her sister.

“Why?” Katerea sarcastically asked her. “I was sure that you of all people would be able to figure out why the two of you were here, but it would seem that intelligence that you’re so proud of is just for show. You’re just as ignorant to what is happening as Rias’ little pet dragon is~.”

“Hey, don’t you dare talk about Rias!” Issei yelled at her, not allowing anyone to insult her in any way. He would kill her if she dared to speak ill of her again.

“Oh, you shouldn’t even try,” Katerea said to him. “As you already know, your powers won’t work in this room, and you won’t be able to harm me. Though if you do insist then I will have to harm you to show you your place since it would seem that your precious master has failed to do so~.”

“Shut up!” Issei yelled, charging right at her, though he didn’t get far. Using the power of her tentacle arms she wrapped them around Issei, stopping him in his tracks, and began to squeeze.

“L-let…go!” Issei tried to yell at her, unable to feel Ddraig anymore.

“Let go of him! You’re going to kill him!” Sona yelled running over to Issei to try and free him, but it was no use.

“It is quite funny that you think that you can tell me what to do, with the weak amount of power you have. You’re so similar to that sister of yours its pathetic~,” Katerea said squeezing Issei harder until he was about to pass out. Though before he did, she lightened her grip, allowing him to breathe again.

“Hopefully the two of you now realize who’s in control~,” she said to the two of them making sure that neither of them would try to fight back again before completely releasing Issei.

“Very good~,” Katerea said, mocking them. “I do love it when people are able to catch onto things quickly like this. It would seem that I have made the right decision after all.”

“Now for as to why I decided to bring the two of you here the answer is simple. You are the precious pawn loved by Sirzechs sister, Rias Gremory,” she said looking at Issei who was concerned that Ddraig was no longer talking to him. The room made it so that neither of them could communicate with the other.

“And you,” she said, looking down at Sona with anger in her eyes. “You are the sister if the arrogant Serafall, the bitch that stole my birthright. The two of you are precious people of the demons that I hate the most. For that reason, I took you from them~.”

“They will come for us,” Issei said to her, believing that Rias and the others would come for them.

“Oh, I would expect nothing less from the people closely associated with the New Four Great Satans,” Katerea said confidently to them.

“Then why would you do this?” Sona asked her, and Katerea respond to her with an arrogant smile on her face.

“Oh, I was hoping that you would say~,” she said, looking straight at Issei before pulling out her staff. “For so long I have been waiting to have my revenge against the New Four Great Satans, and today that will be fulfilled~.”

“You’re going to kill us!” Issei yelled at her.

“Kill you?” Katerea curiously asked him. “Why would I ever kill you? No, my plan is much better than killing you. I shall make the two of you my new family. First starting with you~,” she said looking at Issei while licking her lips.  “I have always wanted a twin,” she said before aiming her staff right at Issei.

“What are you- ahhhhhhhhhhhh!!!”

Without warning, Katerea used her magic to hit Issei straight on with a pink beam. As it made contact with Issei his body began to change.

“Ahhhhhhhhh!” confused and scared all Issei could do now was scream, begging for a release of this pain.

“His skin felt like it was on fire as it became softer and silkier, losing all of the hair on his arms, and turning tan in the process. His eyes changed color, turning purple. His messy hair started to straighten out as it became fuller, growing out to be nearly four feet long, before wrapping itself up into a bun just like Katerea’s. His bones started to crack and break, causing his entire body to change shape, becoming more feminine as time passed.

“Nnnnnnh~! Ahhhh~!” Issei’s screams soon turned into moans of pleasure as Katerea smiled watching his transformation go to its next stage.

“Nnnnnnnhhhh!” Issei’s body surged with ecstasy as his hips began to widen becoming thiccer and in the process his flat ass began to explode outward, forming a giant bubble butt.

Sona was unable to do anything but watch in horror at Issei’s transformation.

It wasn’t long after that a pair of F-cup breasts formed on his chest causing Issei’s mind to become fuzzy. He didn’t have time to care about his new breasts as soon as his manhood was taken away from him.

Though her transformation was done just yet. Her clothes began to melt down transforming into a sexy lacy black thong with a garter belt and into an extremely low-cut dress that had a high slit that exposed a large portion of her breasts. And finally placing a pair of glasses on her face.

Then as Katerea released her magic, Ddraig emerged from Issei's arm and fell to the ground. Currently, Ddraig was nothing more than a red piece of useless metal. Issei was now an exact copy of Katerea. She was her twin.

Making sure that her new twin knew what she was, she used her magic to create a body-length mirror in front of her. Issei looked at her new form in both awe and shock of her new body.

“What have you done to me!?” Issei yelled at Katerea, scared that her voice was the exact same as Katerea’s

“I thought that it would be obvious,” Katerea said to her new twin. “I made you perfect~,” she said examining her new sister.

“Turn me back right now!” Issei yelled at her, pissing her off.

“Haahhh!?” Katerea said, pissed off at that her new twin did not accept her gift with grace. “How dare you talk to me like that!?” She yelled at her, using her magic to wrap her twin’s body up in black snakes made from her magic to make her learn her place,

“Nnnnnh~! Ahhhhh~!” Issei's wanted to fight back but found herself becoming overwhelmed by the pleasure she was experiencing from her new sensitive body. As the snakes slithered across her breasts her womanhood started to twitch but she was unable to do anything to satiate her lust.

“What are you doing to him!? Stop it!” Sona yelled at Katerea. “Change him back right now!”

“Oh my~. It would seem that someone is quite eager to receive their gift~,” Katerea said, taking her eyes off Issei and looking over at Sona.

“W-what are you talking about?” Sona asked starting to get scared. She was worried about what Katerea would do to her after seeing what she did to Issei.

“Aww~. It’s actually cute to see you worried like this~,” Katerea said teasing her. “You know I have always wanted a little sister and Serafall definitely doesn’t deserve Aa cute naïve girl like yourself. As my sister, I can show you who you were always meant to be~.”

“No, stay back!” Sona yelled trying to back away from Katerea, but she continued to get closer to her while continuing to punish Issei. Soon her twin’s mind would become just like hers. She wanted to make sure that once the process was complete that they had a cute adorable little sister to dote on~.

“Shh, there is no use in fighting~,” Katerea said to her. “Just accept your fate~,” she said using her magic to bind Sona in place.

“P-please don’t do this!” Sona said, actually crying, viewing the state that Issei was in. She had never felt so scared before and she knew that if she did nothing, she would end up like him.

“Big sister… please,” Sona said, hoping that her big sister would show up and save the day.

“Don’t worry, big sister isn’t going to harm you~,” Katerea said, gently putting her right hand on top of Sona’s head. “You’re just going to feel a small shock~.”

“Please… don’t,” Sona said one last time to Katerea.

“Don’t worry when I’m done, I am certain that you’re going to love the new you~,” Katerea said, licking her lips.

BZZZT!!!

“P-please!!! Stop!” Sona yelled as she felt Katerea’s magic zap her brain, rearranging her mind bit by bit. At the same time, her hair started to turn brown and started to grow longer.

BZZZT!!!

“S-st-stahp…” Sona said, her mind starting to be rewritten. Her breasts and ass began to grow larger until they were the same size as Katerea’s.

BZZZT!

“B-big sis…ter?” Sona asked herself, not knowing if she was calling out for Serafall or if she was calling for Katerea. Her mind was a jumbled mess right now and she didn’t understand what was happening. Her clothes had started to change into Katerea’s as well.

“Almost there~,” Katerea said happily, seeing how well her new little sister was accepting her “treatment,” without a fight.

BZZZT!

“I…I…. who am I?” Sona asked wondering who she was as her mind no longer recognize herself as Sona Sitri.

“Silly little sister, you’re Saterea Leviathan~,” Katerea gently said to her, she was the youngest of the triplets and was deeply cared for by her big sisters.

“I…I am?” Sona asked wondering if what she said was true.

BZZZT!!!

“Of course, you are~,” Katerea said to her. “You’re my lovely little sister don’t you remember?" Katerea asked her, certain that she was almost fully hers now.

“Y-yeah.. I’m Saterea Leviathan,” she said slowly accepting her new reality.

“And you love your big sister, right?” Katerea asked her.

BZZZT!!

“Y-yes I love big sister!” Saterea said hugging her sister, much to Katerra's surprise. She never thought that she would be this clingy, but she wasn’t going to complain about this. Now there were three of the and there would be nothing to stop them from taking revenge,

After Saterea was fully integrated as her little sister, Katerea wanted to humiliate her two new siblings to cement their transformation.

After an entire day had passed Issei’s or rather Aterea’s reconditioning was complete. She spent hours being shown by her sister the wonders of a woman’s body and having her mind changed to be just like Katerea’s.

She now hated both Sirzechs and the house of Gremory. They were the ones that made her sister suffer and they would pay, but first, it was time for her and her sisters to spend some quality time with one another.

When she made her way down to the kitchen, she saw that their youngest triplet sister Saterea wearing nothing but a cute apron and a cute pair of panties, covered in cream. It would seem that she was trying to make a cake for her sisters.

“Big sister Aterea, I’m sorry for the mess,” Saterea said to her sister. “I wanted to make a cake for our dinner party tonight, but I’m not that good.”

“Nonsense,” Katerea said to her, coming up from behind and putting her finger into the cream and having a taste for herself. “Mmmm~. You’re a natural baker, just as I would like in my little sister,” she said before elegantly standing next to Aterea.

Katerea had made sure to put every quality that she had wanted in a younger sister into Saterea’s mind. She was and, in her mind, has always been their perfect little sister, the youngest of the triplets.

“Come, let’s have the servants finish this for us,” Katerea said to her sisters. “Let’s take a bath and freshen up~,” she said leading them to the bath.

Once there the two twins began to eagerly “help,” their younger sister bathe before dragging her to the bedroom where they forced her to wear a sexy Chinese dress and pose for them.

“Is this alright?” Saterea asked her sisters, hoping that she was pleasing them.

“Perfect absolutely just perfect~!!!” the two older sisters squealed in excitement. For the next several hours they began to play dress up with her. Katerea and Aterea even touch a part of the fun after their cute younger sister begged them to join her.

Both of them were forced to dress up as sexy bunny girls. Katerea dressed as a white bunny girl and Aterea dressed as a black bunny girl. They sat together side by side in embarrassment, though making their sister happy was worth it.

After several more hours of having “fun,” with one another, they were finally interrupted by several knocks on their bedroom door.

“Excuse me,” the head maid said, entering the room. “The ladies’ guests will be here in one how, it is time to get ready.”

“Oh my, is it that time already?” Katerea asked, looking at the clock. “It would seem that we were having too much fun~. Come along girls it’s time to get ready,” Katerea said, as several other maids came in to help them prepare for their guests.

After the hour had passed Katerea came downstairs first wearing a lovely light blue dress. Waiting for her at the entrance of her home was none other than Sirzechs Lucifer, Rias Gremory, and Serafall Leviathan.

“Greetings, I am so glad that you all came~,” Katerea said, literally looking down at them. She had a show prepared for them and she wasn’t going to miss this chance.

“Cease the pleasantries and tell us where they are,” Sirzechs said to her, refusing to let her have her way. They all knew that she was the one that took Issei and Sona, and they were there to get them back.

“Do you mean my sister?” Katerea asked them, pretending not to know about Issei for Sona. “They are still upstairs getting ready, please forgive their tardiness.”

“What are you talking about?” Serafall said to her. “You have no sisters.”

“Oh my, shall I take that as a direct assault?” Aterea asked her, walking down the stairs wearing a sexy black dress and a sexy purple bra.

“Who are you?” Rias asked her, not even realizing that she was talking with Issei.

“How rude~,” Aterea said to her. “You are a guest in our home and have the gall to ask me who I am without introducing yourself first.”

“I’m Rias Gremory, now please tell me who you are?” Rias asked, ticked off that she was right. She would make sure to save Issei no matter what.

“I am Aterea Leviathan, Katerea’s sister,” Aterea said to her.

“Where is Issei?” Rias said, not willing to play games with these sisters.

“I believe that she can answer that question,” Katerea said to her, as Saterea walked down the stairs dressed just like Aterea but in a lovely blue dress and a sexy red bra.

“Sona!” Serafall yelled instinctively knowing that the woman in front of her was her sister. “Sona what are you doing over there!? Come here! Big sister is here!”

“Huh? Big sisters, what is she talking about?” Saterea asked her big sisters, no longer able to remember who she was before becoming Saterea Leviathan.

“Oh, it’s nothing~,” Katerea said to her. “She’s just a little unwell in the head. Don’t worry she will be fixed soon~. How would you feel about having two new younger sisters and a younger brother?”

“Really!?” Saterea excitedly said to her sisters.

“Yes really~,” Aterea said answering her.

“Wait if she’s Sona, does that mean that you’re…. Issei?” Rias asked, hoping that she was wrong, but she wasn’t.

“Hmm? I hardly even remember that name,” Aterea said to her. “Though I can’t say that I don’t feel the urge to return to you and protect you, but that urge can easily be fixed~.”

“Indeed sisters,” Katerea said to them. “It is time to take back what rightfully belongs to us and expand our family~.

“Katerea you are a monster!” Sirzechs yelled at her. “We will make you pay! …Wait what’s going on!? Why can’t I use my magic?”

“I can’t use mine either,” Rias said to him.

“Neither can I,” Serafall said to them, unable to look away from her former sister who looked at her with disgust.

“Worry not, you won’t be needing your magic for now,” Katerea said, blocking all exits off with her magic. “Soon you will be loving members of our family~. Now, who’s first~?”