This is a series of oneshots based on my Kamen Rider x DxD story (updates are slow because I need to piece together a coherent world without leaving too many plot holes). The chapters won't be interconnected unless stated otherwise, although they will stay 'canon' within my world.. I will use the materials mostly from RPG(X) and a bit of TABA with tweaks from my own for the world in my fic so expect canon fuckeries. As usual for a SI/OC type of fanfiction, this serves as a personal fulfillment, sorta power fantasy for myself and hopefully others so it may not be suitable to your taste.

For those who are new and haven't read the aforementioned crossover, my character is a SI/OC-reincarnation with metaknowledge, some 'privilege powers', an Orphnoch form (Kamen Rider Faiz's monster species) and the Kaixa Belt as transformation tool to become Kamen Rider Kaixa, a.k.a KaiSAND. He looks almost the same as Masato Kusaka played by the amazing Kohei Murakami; and his personality is influenced by Kusaka as a result. The SI/OC originally isn't that much of an asshole so you won't see much of Kusaka atrocities, which are depicted in Faiz side materials like the novel and movie.

Alright, now the essential information is done, let's dive into the story.

Yomihara, 2061

I sighed for the fifth time this afternoon, as I had to clean up the mess that my bar's regular guests left behind, including semen and used condoms.. Yeah that was disgusting but I couldn't quit this job since it served as my employer's base of operation within this rotten city. I helped the 'waitress' get up and give her some water.

"Thank you, Kohei-san."

"No problem, Mizuki. It's late now so go get some rest. I will watch for any potential target."

"Aw, don't you want to sleep with me?"

Indeed, she was Mizuki Shiranui, the too-damn sexy female ninja - Taimanin - and mother of big-butt Yukikaze in the future.

I first met her three years prior as she was assigned to this bar to monitor any potentially dangerous 'players' posing threats against Japan. To this day, she was still this bewitching monster as she ALWAYS somehow attempted to flirt and seduce me, her own colleague, but feigned innocence when confronted. I got tired of this bullshit and just injected a powerful dose of anti-mental attacks into my brain to remain calm against Shiranui.

"No. My shift isn't over, and affairs between colleagues usually lead to…undesirable results, both one-night stands or romantic relationships."

My answer was the same as usual; reject all advances and do my job until I was free. Two crushes were more than enough.

Shiranui pouted and used the puppy's eyes tactic on me, which resulted in me flicking her forehead.

"Ouch!"

"We are professionals, not some do you want me to rewire your thoughts again?"

"Ah… No. No, I'm good. Sorry for bothering you, Kusaka-san."

The moment she switched to calling my surname, I knew I had touched a sensitive topic. During my 2nd year working with Shiranui, shits happened and we ended up developing feelings towards each other, having quite a few dates afterward. The higher-ups discovered this and ordered/forced me to break up with her under the pretense of 'no romance allowed in professional work'. I also realized that had my relationship with her continued, I might have screwed the future badly. Now, I'm not too reliant on foreknowledge but, I figured that Yukikaze's character development relied on Shiranui's absence and subsequent brainwashing to become a capable woman as seen in her Future self. I couldn't bet on luck and hoped she would still become such a character.

After months of argument with Shiranui about alternatives, I resorted to using my Orphnoch tentacles to manually rewrite her mind, placing a blockade on her thoughts that tormented her whenever she thought of me as a lover, rewiring her feelings to love another guy who was chosen from the Mizuki clan. It really pained me seeing her after that but being a dog for a traditional assassin organization left me no other choice.

"...Tch."

I clicked my tongue in frustration as I watched Shiranui's back retreat into the back room.

Yomihara, 2062

I was relieved of my position as undercover agent and was rewarded with quite some cash. I was wandering aimlessly on the streets when I saw someone I never expected to see here of all places.

"Buhiiii, demon knight is mine!"

"N-No, stay away from me!"

That was Ingrid, your poster girl of dark-skinned hot gal. I had no idea why she wasn't with Edwin Black, seeing that supposedly she had become his top enforcer many years ago. She looked…awful, with swollen spots on her body and stains of semen stuck on her skin. Seeing that bystanders were trying their best minding their own business, I decided to be a decent human being this time. Good thing the Kaixa Belt was always with me.

9 1 3 ENTER

STANDING BY

"Hey pig!"

"Buhiii, who's dat?!"

"Your butcher. Henshin."

COMPLETE

In a flash, I became Kaixa and jumped at the orc, delivering a punch to his pig nose. The impact sent him backward into a nearby building. I quickly checked on Ingrid and urged her to run.

"W-Who are you?"

"Just a passing through Kamen Rider, remember it. Hide somewhere and wait until I roast this pig."

I said to her, just in time for the orc to show up again with a metal bar as his makeshift weapon. Sure thing, weapon for a weapon then. I un-strapped the Kaixa Blaygun and pulled the hammer, toggling the Gun Mode. The pig made fun of my baby, calling it an oversized toy, so I countered his words with two shots to his kneecaps, vaporizing the bones and severing his legs. The following shriek was annoying enough for me to switch to the Kaixa Shot.

READY

EXCEED CHARGE

I hit the ENTER button as a surge of energy traveled from the belt into my hand holding the knuckle, ending with a loud beep. I gripped the handle and ran into the Orc before pressing the side button and executing Grand Impact. The monster exploded immediately and the remains burst into blue flames until only ashes were left, a big X symbol was imprinted on the pavement.

Ingrid was speechless at the utter destruction of her almost-raper and was recoiling in fear as this Kamen Rider turned to her. He sighed out loud and removed the phone? on the front of the belt, then a blinding light engulfed him and turned him back to human form.

"So, impressed?"

I lent Ingrid my coat and led her back to my apartment. She looked uneasy but then relieved after a long bath and a cup of hot coffee. I started asking her questions about herself, her boss and how she ended up on the street, dressing like a prostitute. Her explanations were lengthy so I grabbed a notebook and wrote down the essentials:

-Scouted by Edwin Black but assigned to Bismarck as temporary subordinate as Black was gone doing his shady business.

-Nomad's internal conflicts happened and Ingrid was blamed as one of the initiators and sold to Under Eden brothel.

-Escaped from captivity but ended up in another brothel.

-Escaped again and was pursued by Noman agents, which the pig earlier was one of.

"...Wow, your life is kinda shitty huh."

"Crude language, but more or less correct."

I put down the notebook and looked at her while pondering. While the revelation was unexpected, it ultimately served me no significant purpose. She wasn't overly loyal to Black, nor fervently waiting for his return because his time as Ingrid's boss was about one week at most.

"Kusaka Kohei, you said you are a mercenary working for the Taimanin mainly. How is that possible?"

"Call me a handyman, but yeah I do work for Taimanin groups most of the time. Circumstances forced me to be their dog, lest they would allow the UFS to come kidnap me. I can assure you that no sane people want to be involved with the UFS."

"I see. Still, why would you, a man shown to hate infernal beings, save a Hell Knight like me? Is there any hidden agenda? If so, I'm afraid that I do not hold crucial information about Nomad, now that Bismarck has reorganized it."

"Oh c'mon, can't a man act like a decent human being? Sure, you look sexy." I pretended the luminous blush on her face didn't exist. "But if I wanted to see sexy ladies that badly, I could just go to brothels. I ain't a sleazeball."

Ingrid sighed in relief at my words. After that, Ingrid began living with me to stay under radar and hide from Nomad pursuit. She taught me some swordsmanship that didn't go well with how I handled the Kaixa Blaygun; in return I gave her some firearm lessons in case I needed more firepower. She was curious about the Kaixa Gear so I gave a quick rundown of it alongside a demonstration. As expected, she wasn't compatible with it but at least, she wouldn't burn into ashes, just got electrocuted.

We went for some missions that involved busting some brothels and rescuing captive Taimanin. Had a run-in with Shiranui who looked like the whole world came crashing down on her, what an awkward moment. Ingrid didn't ask much about the bouncy Taimanin so I ignored the issue.

We maintained a good, healthy friendship until one day, I was too drunk and, uh, did it with her. She was surprisingly encouraging of this throughout that night. Turned out she owed me a lifetime debt of gratitude for the rescue and shelter, which inevitably evolved to love. Fuck, now I became the Edwin Black in her eyes that the current living Edwin Black couldn't. After that was a series of days in which Ingrid tried her best to seduce me and I tried my damn best to ignore her advances.

Goddammit, I eventually caved in and gave her a rough, romantic night. Sorry my fellow dudes, I couldn't contain my lust.

"So, this happened."

"Indeed, my dear."

Ingrid nudged closer to me on the bed, basking in the afterglow of the sex. I rubbed my temple, still not believing at all. Look on the bright side - now I have secured the loyalty of arguably one of the most powerful allies you could get in the Taimanin world. I thought about the abandoned plans, the ones I devised to change the course of events. I possessed the powers and near-immortality of True Orphnoch, with never aging as a bonus, so I had more time to wait and act.

I looked at Ingrid; it would have been better if she stayed in Nomad so I could have a double agent disrupting the Chaos Arena.

"You know Shiranui, the busty Taimanin you met last month?"

"Oh, that jealous woman. What about her? Are you going to make her yours?"

Damn, Ingrid was observant.

"I'm not, or rather, I couldn't. Stuff happened and we broke up." I closed my eyes, remembering the times we were together. Shiranui was the wet dream of anyone who played Taimanin, me included. Too bad job ethics and my personal feelings got in the way.

"Yet, you still have feelings toward her." Ingrid's gaze was cold, but then she smiled and kissed my cheek. "Don't worry. As long as I still have a place in your heart, I'm content with the idea of harem."

"Ersh, don't speak that word. I'm not a horny teenager."

We slept afterward and next morning, after breakfast and training, I began to list some of my contingency plans that involved Ingrid to her. At a certain point during the year 2077, Shiranui would fail her mission in Under Eden and be held captive for brainwashing by Real Yazaki and the Incubus King. Ingrid's job was to secure an infiltration route for me to get inside and place a backdoor in Shiranui's mind, preventing her from completely falling into the Incubus King's thrall. That way she could become a double agent for the Taimanin faction.

"Why don't you just do that to her now?"

"My ability requires an external reset, spell, device, etc on the target's mind. I can't manually remove the previous command and place a new one easily."

Demons were less susceptible to my power, as demonstrated on Ingrid when she confessed her feelings to me and I attempted to rewrite her brain to remove that. Otherwise, I would just crash into Kuroi's palace and do that to him myself.

The problem right now was how Ingrid returned to Under Eden without being executed by Nomad or tortured by Real, who was furious that one of his better money-making SOWs had disappeared. Looks like I would need the assistance of the Koukawa clan, who specialized in spywork. Finding one was easy as the owner of the bar was Oboro, his former employer. The difficult part was that I really hated her, partly because of lingering rejection from her back when I was still an eager young man who tried to impress his sexy boss and that she was the reason why the Taimanin was able to catch me in their webs.

"Guess we have to wait for an opportunity to come."

Gosha Village, 2065

Three years after Ingrid became my enforcer, I managed to fix the bridge between me and the big clans in Gosha by taking many vital missions and agreeing to mentor some of the next generations like Murasaki who was somewhat immortal like me, cultivating in Oboro helping me to re-introduce Ingrid to Under Eden. Took quite a long time to add the spiritual command to her mind that as long as I lived, she wouldn't get mind-broken and the command wouldn't be discovered easily. The command was powerful enough to force Ingrid's body to ignite the implant chips like EVE and the Chimera Chips. I had no idea how long this farce would last but in worst case scenarios, I would have to crash Under Eden and rescue her.

Later that year, I was invited to celebrate the birth of the Fuuma clan's male heir. Attending the party were a variety of familiar faces such as Asagi, Sakura, and Shiranui carrying the infant Yukikaze who I tried to avoid. This was just a ruse so that I could meet up with the Fuuma council and discuss the upcoming revolt. I was against it, saying that a freelancer like myself needed a clean background, so they decided to hire me to do some dirty work.

"What the…?"

I got to meet Fuuma Kotaro, the upcoming harem protagonist, and something about his presence made me want to transform into my Orphnoch form and kill him. After a moment of clarity, I thought that maybe it was a residue of Edwin Black from the TABA timeline reset and it triggered my primal instinct. Gotta keep an eye on the brat in the future.

After signing the contracts and receiving half of the cash, I got out of the Fuuma mansion and wandered aimlessly around Gosha. A 7yo Kousaka Shizuru was practicing her whip in the forest. For someone later becoming the seductress Flower Taimanin, she sure was hardworking in the young ages.

"Ah, you are…"

"My name is Kusaka Kohei, just a handyman. Are you too young to stay up late training like this?"

"Um! I will become a great Taimanin and vanquish demons, protecting the world!"

Oh god, the innocence of a child…

"That's a good goal. I hope you can achieve your dream, Kousaka-chan."

"Hehe, thank you Onii-chan. Oh by the way, can I ask for your number Onii-chan? For pure purposes of course ❤️"

Aaaand there was the Shizuru I know. She nonchalantly asked for my phone number with a bewitching smile unfitting her age and appearance. I sighed in defeat and did as she asked.

I stayed long enough to watch Shiranui feed Yukikaze from afar in my Kaixa form, which was lucky given that she had seen my transformation before. Yukikaze's baby form was a bit difficult to recognize but upon hearing her mother call her name, my worry was gone. I jumped down from the opposite building and was about to get on Side Basshar when, to my surprise, Shiranui opened the windows and was looking at me. She was saying something that I intentionally ignored and I shook my head before driving off.

What I didn't see was that Shiranui's hand briefly turned gray and a small drop of ashes fell off.

As expected, the Fuuma revolt shook the entire world of Taimanin. Needless bloodshed and slaughters were not my thing so I opted to stay out, even when Fuuma Danjou threatened to send assassins after me. I just laughed at his words and transformed into Kaixa, killing his troops and holding Danjou long enough until Oboro and Asagi arrived. I cocked the hammer and fired the binding shot from the Kaixa Blaygun to lock Danjou in place, leaving him to the other Taimanins to deal with.

"Kusaka, wait!"

"I have other matters to attend to, Igawa-san. Oboro, I suppose our deal is still valid?"

"Hm, of course."

"I see, that's good."

VEHICLE MODE

I hopped on Side Basshar, who had done its sharing of slaughtering ninjas, and sped out of the burning field.

Later on, I received news from Ingrid, who had successfully established a good position in Under Eden. The self-proclaimed Incubus King was in a cold war with the real Incubus King, Kamadeva. Kuroi and his underlings were looking for new minions and had considered kidnapping Shiranui, seeing her power as the current strongest Taimanin. The Fuuma revolt had delayed their plan as infiltrating Gosha would be a death sentence to demonic beings.

"There's still time. Let's go fetch Kurenai."

Following the fall of Shinganji clan, I had granted Kurenai and Makishima Ayame shelter in my new house. As Kurenai was still young, Ayame had to do odd jobs to make a living for both. Their pride didn't allow them to use the money I left behind. Still, I repeatedly warned Ayame not to do dangerous missions lest Kurenai would be left behind. I knew the events of Taimanin Kurenai would eventually happen; it's part of Kurenai's character after all.

What I never anticipated was that Shiranui's disappearance had happened earlier than my calculation.

Under Eden, 2075

Under the guise of a high-ranking Nomad officer, I entered the brothel and met Ingrid in the rendezvous location. According to her, Shiranui had been held here for 8 days and still showed signs of resistance to conventional brainwashing processes. What worried me was that Real gave up and contacted Kuroi to ask for the EVE Chip, which posed great danger to my plan as I hadn't implanted the protection command on Shiranui's mind yet.

"Kohei-sama, you can use your monster form to blend in and enter the VIP area, where Mizuki Shiranui is. With your forged papers, it's easy to gain a VIP card and ask for her."

"Good idea, Ingrid."

I concentrated as markings appeared on my face and body before transforming to my Wyvern Orphnoch form. I then followed Ingrid to the lounge and presented my card for the VIP upgrade process. Once it was done, I headed upstairs and encountered Real, who was fuming about something.

"Oh good evening, Mr. Julius. How can I help you?"

"I have heard rumors about this new prostitute in this place. I suppose my privilege is enough to order her service?"

I showed my card to Real and the fatass nodded multiple times. He made a call and after minutes of talking, told me that Mizuki Shiranui was in the 1st VIP room. I thanked him and left.

Once I entered the room and locked the door carefully, I shot my finger tentacles at the corners where the hidden cameras were and disabled them for an hour, enough for me to talk to Shiranui. When I was sure that the cameras were now playing on loops, I reverted to human form and walked to the shivering Shiranui, who looked like she was just done being sexually tortured. I tapped her arm lightly and she slowly woke up, seeing my smiling face.

"Ko, Kohei-san…? Kohei-san!"

"There there, I'm here."

I patted Shiranui's back as she began crying. I waited until she calmed down and let her go, not noticing her slight pout.

"I got wind of your kidnap, Shiranui. While I cannot get you out of here, not without a big fight, I can do something to help you resist the brainwashing process."

"You know? How?"

I smiled bitterly.

"I sometimes have visions of the future, some are clear and others are hazy and undefinable. I see scenes of you being captured, put into machinery to have your woman parts tortured." I sighed. "Perhaps it was these visions that I did the unforgivable thing to you back then."

Shiranui took a while to process this and when she did, she slapped me and kissed me afterward. I was dumbfounded and she took this as the chance to shove her tongue inside my mouth.

"Nru…Pero pero…"

"Wait…Wait, Shiranui! What are you doing?!"

I was seriously out of breath and was desperate to get Shiranui out of me. She eventually let go of me and said to me with what might be the happiest smile I had seen from her.

"Oh Kohei-san, I knew it. I knew you never wanted to do it. I knew it, I always knew…"

"But, what about the thing I had done to you? Shouldn't it give you pain whenever you think of me?"

"Hmph, never underestimate the power of love. A little pain cannot stop me."

I stared at her with my lower jaw stretching wide in disbelief. She resisted my power? Had she gone through the process of becoming Succubus that early?

"Now that you have confessed the truth, I will no longer hesitate. I will endure this humiliation as long as you want, Kohei-san. I will prove that I'm better than that Hell Knight harlot!"

"But… What about your husband? And Yukikaze? Siding with me means abandoning them."

Shiranui's eyes widened and she stayed silent for a while. Then she just smiled at me.

"I love Natsuo a lot, he has been quite a decent husband to me. But you Kohei-san, you mean much much more to me. I would even gladly kill the Mizuki elders for forcing such orders on you myself."

"I… Dammit, I shouldn't have behaved like an idiot and wooed you. Come here, you vixen"

I gritted my teeth and went for a deep kiss with Shiranui, pushing her down on the bed. While we were making love after years, I carefully calculated the clock and after ejaculating in Shiranui for the fifth time, I began to explain the plan to her.

"From now on, there will be a tough time for you. If I leave you be, the Incubus King will try his damn best to convert you into an obedient Succubus slave. Unfortunately for him, I'm here."

"Even if he tries, I won't fall."

"Don't underestimate magic, Shiranui. Especially from one of the nine Hell Clans like Incubus."

I transformed my right hand into Orphnoch form.

"To counter mind-manipulating magic, a similar but more powerful one is needed. Now, I will place an absolute command in your brain that no matter how broken your mind is, your consciousness can still stay strong enough to snap you out of it. This will be in effect as long as I remain alive."

"Ufufu, what a devious plan. This way, Real and the Incubus King can never fully force me into their servitude. I suppose that we will stay in contact?"

"Of course. I may return to this wretched place for you, or you can contact me via Ingrid. Don't antagonize her too much, alright? Someone as loyal as her is hard to come by."

"Hehe, I will try."