Four days before departing for Tokyo, deep underground the Kyoto Akatsuki Trading Company. Rough impact sounds and panting breaths echoed through this secret underground training hall, fortified by Tamamo's barriers and magecraft.
"Haa... Haa...!"
Drenched in sweat, I kicked off the floor and sprang forward again. A charge that pushed my oni physical abilities to their limit. A speed difficult for human eyes to follow, but to the opponent blocking my path, it was merely a slow rhythm.
"Master, your movements are too honest, don't you think? Can you catch Tokyo's demons like that?"
A languid, bewitching voice. Berserker, Shuten Douji, held a sake cup in one hand and lightly caught my full-power punch with two fingers of her other hand.
Boom!
The sound of air ruptured, but she didn't even flinch. An overwhelming gap. Her Strength was of the mythical EX rank, perhaps even surpassing Muzan, the progenitor of oni.
Before her, who received fame bonus, land bonus, and even Mad Enhancement buff, my physical abilities were no different from a child's struggles.
I stepped back, creating distance, and gritted my teeth.
As expected... is this the limit of my physical abilities?
For the past five years, I dominated Kyoto's darkness and devoured countless evil people. My Blood Demon Art grew stronger daily, allowing me to command seven heroic spirits and wield Blood Demon Arts proficiently.
But ironically, my oni body had stopped growing. My current physical specs remained at the level of a lower-tier Lower Moon, or perhaps even worse.
The reason was clear. There were only three ways for an oni to become stronger: eat an enormous number of humans, devour strong oni, or receive Muzan's blood.
There were no oni to hunt in Kyoto, and Muzan's blood was even more impossible to obtain. All that remained were humans, but eating only humans had a clear growth limit.
Just as Kyogai in the original story reached his limit from eating humans and was stripped of his Lower Moon rank, I too had reached a plateau where I could no longer enhance my body's strength through mere consumption.
A talented oni might grow stronger with little sustenance, but unfortunately, my oni talent wasn't as high as Doma, the Shabana siblings, or Kaigaku. Of course, they received thick Muzan blood, but that means they were recognized by Muzan for their power and talent.
My oni talent isn't at that level. I've even eaten rare blood and made efforts, but is it still far off?
"Hmm~ Master, do you have time to be distracted?"
Shuten Douji closed the distance in an instant. I reflexively raised my arms into a defensive stance, but she mocked my defense as she burrowed into my embrace.
"Here, an opening."
Her hand softly grasped and held my extended fist. An unshakable grip. The next moment, she pulled me strongly toward herself.
"Uh...?"
My body, losing balance, ended up being held against her small yet soft chest. The moment the sweet sake smell and dangerous oni scent pierced my nose, Shuten Douji's hand wrapped around the back of my neck.
"Got you."
Smack.
A soft, hot sensation touched my lips. Shuten Douji covered my lips as if she'd forgotten we were sparring, or as if this too was part of the spar.
"Mmph...?!"
When I panicked and tried to push her away, she instead pressed deeper. Her tongue ravaged my mouth, mixing with thick saliva.
While restraining me with overwhelming power, she explored me as if rolling candy. Simultaneously, her other hand slid into my gi trousers and began caressing my crotch.
My mind went white. In that moment of pleasure and bewilderment mixed, I realized I needed to activate not my oni instinct, but my authority as a Master.
"Stop...! Halt, Shuten!"
What erupted from my mouth wasn't a simple shout. It was an absolute command, subordinate to my Blood Demon Art, .
In that instant, Shuten Douji's movements stopped as if lying.
"..."
Her pupils still glittered with desire, and the hand inside my trousers twitched regretfully, but her body froze like a statue, unable to refuse my command.
This was another power of my Blood Demon Art, and its most terrifying aspect. Over the heroic spirits I summoned—strictly speaking, created based on my memories and power—I held absolute dominion.
In the Fate world, Command Spells are forced command authority through magical energy, but Servants can resist depending on their Magic Resistance or will.
But commands through my Blood Demon Art were impossible to resist. It was like directly inputting code into the brain, allowing perfect control over their thoughts and bodies.
"Puh...! Shuten, what are you doing in the middle of sparring."
As I gasped for breath and escaped her embrace, Shuten Douji finally licked her lips as if the stiffness had lifted.
"What a shame~ The mood was good. Master, was there a need to use a command? I'm ready to be devoured anytime if Master wants."
"We agreed to spend tonight all together. No cutting in line."
"Tch, so inflexible. Though Master's restraint is kinda hot too."
Shuten regretfully gave my crotch a quick glance and stepped back. I adjusted my clothes and sighed.
If my body's growth had stopped, I had to at least polish my techniques. But facing Shuten bare-handed was closer to one-sided ravishment than technique practice.
Then there was only one method.
"Okita."
I called Okita Souji, who was waiting with a towel in a corner of the training hall.
"Yes! Master! Do you need a towel? Or water?"
She cheerfully ran over. I shook my head and looked into her eyes.
"No. Lend me your body for a moment."
"Ah, you mean possession? Of course! If my body is fine, please use it as you wish!"
Okita nodded without a moment's hesitation. My heart ached at her complete trust.
"Thank you. I'll return it soon. Blood Demon Art,
."
My pupils glowed red as my spirit left my body. With a floating sensation, my consciousness was sucked into Okita Souji's inner self before me.
Thud.
My original body collapsed to the floor like a puppet with its strings cut, and Shuten quickly caught it. I saw the world again through Okita Souji's eyes.
Light. Unbelievably light and sharp compared to my dull oni body. Assassin Okita's body without the Weak Constitution skill was a killing weapon optimized for wielding a sword.
"Hoo..."
I exhaled through Okita's mouth and drew the Kashuu Kiyomitsu (sword) at her waist. Okita's muscle memory synchronized with my consciousness. The subtleties of swordsmanship I hadn't known began to be understood instinctively.
"Ooh~ So it's the genius swordsman this time? Master, wanna have a go with me in that body?"
Shuten Douji carefully laid my original body in a corner, then flashed her eyes with interest.
"Yeah. With this body, I should be able to keep up with your movements a little. Here I go, Shuten!"
I kicked off the floor.
Shukuchi
I instantly closed in on Shuten. It was a speed on a different dimension from when I charged recklessly with oni strength. A swift strike as if shortening space.
Not a three-stage thrust, but a powerful thrust that could pierce steel. Though an Assassin, Okita is also a Japanese heroic spirit. Moreover, in this world, Okita Souji hasn't been dead for very long, and with her current high fame receiving fame and land bonuses, her body was powerful.
My thrust aimed simultaneously at Shuten's neck, heart, and abdomen.
Clang! Clang!
But Shuten Douji was smiling. Without even setting down the sake cup in her hand, she deflected the blade with her bare hand and twisted her body to evade the thrust.
"Definitely fast. But, Master. Even with Okita's body, if the core is you, there's a limit, don't you think?"
Shuten's eyes shone strangely. Her agility surpassed even Okita's (excluding Shukuchi). The moment my attack ended, in that split-second opening, she was already behind my back.
"Uh...?"
"Full of openings."
Grab.
A strong force embraced me—Okita's body—from behind. Shuten's arm wrapped around my waist, and her other hand tightly grasped Okita's chest.
"Hyaang?!"
A strange moan in Okita's voice burst from my mouth.
"Master, this body is quite soft, isn't it? Does our Master show such cute reactions even when inside someone else's body?"
Shuten breathed hot breath into my ear and tried to slip her hand into Okita's hakama.
"How about rolling around with me in Yasusada's body like this? That'd be pretty blasphemous and hot too. What about scissors or a clam kiss?"
A whisper laden with thick sensuality. Okita's sensitive senses reacted excessively to Shuten's touch. My legs nearly buckled from the spine-tingling pleasure.
Th-this is dangerous!
I hurriedly focused my mind.
"Release!"
Ping!
With the sensation of consciousness being flung away, I returned to my original body. What I saw upon opening my eyes was Okita's figure, face red as a beet, being held in Shuten Douji's embrace.
"..."
Okita became aware of Shuten's hand kneading her chest and Shuten's lips touching her ear. And the sensations her body had felt just moments ago flashed through her mind.
"You... you pervert oniiii!!!"
Wham!
Okita's powerful headbutt slammed into Shuten's jaw.
"Oww?! Hey, you're hitting me! I was just playing with Master!"
"Who's Master! What were you trying to do with my body! Master, you're really awful too!"
Okita huffed and ran to me, making a tearful face. I sweated profusely and apologized.
"S-sorry, Okita. I didn't think Shuten would do that..."
While settling the noisy training hall, I sank into thought for a moment.
The absolute command that stopped Shuten's mischief. And the possession that controlled Okita's body as if it were mine. And I can also manipulate their minds. Not just physical commands, but even memories, common sense, and personality can be altered.
When I changed Nobbu's common sense to believe women pee standing up, she was thoroughly teased by Okita for peeing standing up. Not only that, I had a feeling I could alter personality too. Of course, I didn't do it because it felt like toying with them like playthings.
All of this suggested my Blood Demon Art wasn't limited to mere summoning.
Tamamo-no-Mae once proposed this hypothesis to me.
`Master, we probably aren't real heroic spirits from the Throne of Heroes.`
They have memories from their lifetimes. Their Noble Phantasms, skills, and power are identical to the originals. But crucially, their memories right before being summoned—that is, memories from Chaldea or with other Masters—were hazy like fog.
`Perhaps Master combined the knowledge inherent in your soul with your power as an oni to create our concepts in this world?`
Not summoning heroic spirits from parallel worlds, but beings created by breathing souls into characters I know. That's why they had the structural characteristic of being absolutely obedient to my commands.
Because I myself am their creator, no different from a father.
When I heard that hypothesis, I was momentarily confused. Then are these people laughing and chatting before me fakes? Dolls created by my delusion?
But I shook my head.
"No."
Okita's flushed face pouting before me now. Shuten's smile as she teases and enjoys me. Tamamo's devotion creating fake ledgers for me above ground.
Whether they're created beings or summoned beings, that doesn't matter. They love me, and I love them too. We share each other's warmth, eat together, and talk about the future.
"Master? Why are you spacing out again?"
Kiyohime had come down at some point and poked my cheek.
"No, just. I was thinking I'm glad you're here."
At my words, Shuten, Okita, and Kiyohime looked at each other, then brightly smiled.
"Of course. Because we're Master's."
"That's right, Master! We're always Master's sword and family!"
"To be precise, we're married."
I stood up. Although my body may be weak, I have such powerful and lovely other halves.
"Let's go. Everyone must be waiting. We need to prepare the final banquet before heading to Tokyo."
"Ooh~ Can I look forward to tonight?"
"M-Master! I, I need mental preparation... but if Master wishes!"
"The first one is obviously me, right?"
"No, that's not the banquet I meant. So you were all full of intentions anyway?"
We left the underground training hall noisily laughing. The night of 1905. Our hunting preparations to hunt real monsters were nearly complete. We will stride unabashedly into Tokyo, into that demon capital, into the darkness where Muzan awaits.