Even though everything has returned to normal after Kagerou and Ei's wedding, Kirigami is still in his internship so he will still have to continue interning with Kagerou a.k.a his adoptive father. 

(The Next Day After the Wedding)

Kagerou and Kirigami are fighting each other using their Quirk Nexus. Both of them fired antimatter rays at each other, then absorbed and released them, creating a cycle. Kagerou then jumped into the air and created a spear.

Kagerou: LONGINUS CRUSH!

Kagerou holds the spear the way a fisherman has a spear to hunt fish. He then jumped down and stabbed his spear into the ground, creating a shockwave that pushed Kirigami back.

Kirigami: "Thought" Chimera, plus One For All, plus Mechanize, along with Nexus 5,25%!

The air was thick with anticipation as Kirigami's hands morphed into formidable wolf-like claws, enhanced by state-of-the-art mechanical armor. Fueled by a surge of adrenaline, he lunged forward, his claws cutting through the atmosphere as he unleashed a flurry of rapid, powerful strikes aimed at Kagerou. Yet, Kagerou maintained his composure, deftly evading the barrage with remarkable agility. Although he could not replicate Kirigami's other Quirks, the extraordinary power to freeze time granted him a distinct advantage. In a striking shift, Kagerou tapped into his inner strength, transforming into a magnificent nine-tailed fox and launching himself into the battle to face Kirigami directly.

Kirigami: So this is your fox form...

Kagerou: Yup...but... Unlike Miko and Sakura, I can also control fire instead of only lightning!

Kagerou unleashes a barrage of fireballs from his mouth, targeting Kirigami directly; however, Kirigami skillfully absorbs the flames and sends them back at Kagerou with triple the intensity. In response, Kagerou conjures a katana forged from lightning, slicing through the oncoming fireballs with precision. The severed halves of the fireballs then separate further, propelling themselves back and resulting in massive explosions.

Kagerou: Not bad at all, son.

Kirigami just gave a smirk and drew his sword towards Kagerou and the two began to use swords to fight each other.

After a few minutes, they pointed their swords at each other's necks.

Kagerou: Draw.

Kirigami: Damn...

Following their training session, Kagerou and Kirigami made their way back to the recovery room to recuperate. Kirigami was taken aback by his father's adeptness with weapons, but what truly astonished him was Kagerou's remarkable understanding of his preferences, despite having only been his father for less than a day. Kagerou was already aware of Kirigami's hobbies, favorite foods, drinks, and even the items he disliked. In a heartfelt gesture, Kagerou offered Kirigami a cup of lemon tea, marking the first time Kirigami experienced a sense of paternal care.

Before his encounter with Kagerou, Kirigami often felt a pang of jealousy when observing other children with both a mother and a father. It had been over 11 years since he had seen or heard from his biological parents. Although Kirigami had formed bonds with Ei, Makoto, and his friends, the feeling of jealousy lingered, as he yearned for the familial connection that had long been absent from his life.

Kirigami: Hey Dad, I have a little question... Why did you choose me for the internship? Because up until now, you have never accepted anyone as a student except Focalors and Mavuika.

Kagerou: How should I answer that now... Besides the fact that you have the Nexus, I have other reasons. It's not because I want to win your favor to get to Ei or to get the Nexus back. It's because... I saw myself in you—a young, rebellious, disobedient, and murderous me as a Rider. 

Kirigami was surprised by that answer.

Kirigami: You saw yourself... in me?

Kagerou: I never reveal my past to the public. Only those I trust know about it. "Put his cup down" Ever heard about Quirk Marriage?

Kirigami: I heard about that, well... Endeavor Jr told me about it.

Kagerou: Well then, skip the concept explanation. My father, or your late grandfather, Shinomura Mikage, was also forced into a Quirk Marriage. And your late grandmother was his second wife, the first wife was a Chinese woman. Both my father and she had a daughter who was also my half-sister. Both of them did not like a Quirk Marriage, so they divorced after about 5 or 6 years, but he still provided enough money to raise his daughter.

Kirigami: Does Auntie Miko and Auntie Sakura know about her?

Kagerou: They knew. And... well, he told them about her and his goddamn Quirk Marriage. 

Kirigami: So I'm pretty sure that half-sister also has the Fox Instinct Quirk...

Kagerou: You could say that... Cause her Quirk is kinda a mix between my father's Fox Instinct and her mother's Wolf Instinct. 

Kirigami: Ok...

Kagerou: Where was I, oh right. After his divorce, he found a new love. That was my biological mother, Yae Kasumi. And you know what happened next.

Kirigami: You, Auntie Sakura then Auntie Miko.

Kagerou: Yeah, they were only born after me about 2 years. But...that's when my rampage started...

Kirigami: Why?

Kagerou: Domain Expansion... Remembrance...

Kagerou and Kirigami found themselves in a house that seamlessly blended modern design with traditional Sengoku period Japanese architecture as a space materialized before them.

Kagerou: Perhaps you should experience that memory yourself.

After that sentence, a man with silver-white hair and blue eyes quickly opened the door and entered the house. Next was a girl with pink hair who was holding Miko and Sakura when they were only 3 years old.

Kirigami: They are...

Kagerou: Your grandparents and your aunties when they were young. 

---------------(Remembrance)---------------

Mikage: Damn it! They have gone too far!

Kasumi: Hun...

Mikage: Don't worry. I won't let them harm you and our child. I promise. 

Young Miko: "Scared" Papa... I'm scared!

Young Sakura: "Scared" Mama... where is Ani-chan?

Kasumi: There, there my little fox girls. Mama and Papa are here.

Mikage: Your brother is in his room. He will be there with you. 

???: Aw... how sweet...

Mikage and Kasumi shifted their gaze in the direction of the sound. Standing in front of them were a pair of elderly individuals. Despite their grey hair, the woman bore a striking resemblance to Mikage, while the man shared the same eye color as Mikage.

Kirigami: Are they...

Kagerou: "Grins" Your deadbeat great-grandparents.

Mikage: Father... Mother... 

Mikage's Mother: Oh... you still have this mother? After you divorced Lingxin and didn't even bother to ask for custody of Feixiao? You little brat!

Mikage: "Grins" Shut up! Neither Lingxin nor I want a loveless marriage! Feixiao is indeed my daughter, but I want her to still have Lingxin by her side! I won't let you use Feixiao as a weapon for your rotten ambitions!

Mikage underwent a rapid transformation, assuming the shape of the Nine-Tailed Fox, and readied himself to launch an assault. In response, Kasumi swiftly retreated, holding Miko and Sakura protectively in her arms. 

Mikage's Father: You could have chosen a better woman to be your wife. But you... you chose a poor and lowly daughter! Our Shinomura family will not accept that trash and your three abominations!

Kasumi: I may not be rich and I may not be from the upper class! But Mikage loves me for who I am! Call me trash or lowly like you want! But... "Ignites her flame" Never... call... our children are abominations!

Mikage's Mother: Stay away from our family, bitch!

Mikage's Father: The choice is yours, son! Either follow us... or die with her!

Mikage: I rather die!

Mikage's Father: What a pity, you could have inherited the Shinomura family business. But if that's your choice... we'll grant your wish! But first...

Mikage's mother directed her hand menacingly at Kasumi, Miko, and Sakura, poised to deliver a devastating strike. In a swift motion, Mikage instinctively stepped in front of them, determined to shield her friends from harm, embodying the timeless belief that, much like in fairy tales, love ultimately prevails over adversity.

Mikage's Mother: Farewell...

A dark sphere of energy surged directly toward Mikage, Kasumi, Miko, and Sakura. In resignation, Mikage shut his eyes, bracing himself for the inevitable fate that awaited him and his family. However, after what felt like an eternity of more than ten seconds, he opened his eyes to discover that he, along with Kasumi and their two daughters, had miraculously survived. 

Young Miko+Young Sakura: "Scared" Ani-chan...

The unexpected appearance of the 5-year-old Kagerou caught everyone's attention almost immediately. Yet, in that instant, his eyes did not reflect the vibrant blue commonly linked to his father, nor did they exhibit the gentle pink tone associated with his mother. Rather, they displayed a mesmerizing and mysterious purple hue, radiating an elusive yet undeniable aura of lethal intensity.

Mikage's Father: So... this is your son... 

Mikage's Mother: Huh... you still have your guts to come here, huh?

Mikage: "Yells" KAGEROU, RUN!

Kasumi: "Yells" LISTEN TO YOUR....

Young Kagerou: I... I will protect my family... And create... my ideal world. Even... if my hands are stained with the blood of the enemies... I will not hesitate... to let myself... go deeper into the darkness...

Mikage's Mother: What are you blabbing about, brat?

Kasumi: Kagerou, I know... 

Just as Kasumi was about to offer her guidance, Kagerou fastened the Desire Driver around his waist. He then placed the X-Geats ID Core into the central socket of the Driver. A black flame ignited on his right hand, and from that flame, a Buckle materialized.

(X-Geats Buckle)

Mikage: Son? What are you...

Kagerou then splits the buckle into 2 separate parts 

(X-Geats Buckle Separated)

Buckle: X-GEATS!

Kirigami: Is that...

Kagerou: My first form I achieved... Also... the first time I am... Kamen Rider...

Kagerou then inserts both of the buckles on both sides of the Driver

Desire Driver: BLACKOUT!

Young Kagerou: Henshin...

He activates the Revolve mode of the Driver and then spins the Driver 180 degrees. Then at the final touch, he presses the right side of the Buckle. Nine brilliant flames, tinged with hues of black and purple, burst forth from the nine segments that reflected Buckle's nine fox tails. From the fox's visage emerged a sleek, obsidian creature marked with dark blue stripes—a powerful nine-tailed fox that charged at the two figures Kagerou should have recognized as his grandparents. After executing its rapid assault, the fox returned to Kagerou, transforming into a formidable suit of armor. This armor integrated seamlessly with Kagerou's body; its eerie purple eyes shone with a menacing light, while the swirling jet-black flames radiated an atmosphere of dread and impending doom.

https://youtu.be/cCn4TPxvjOk

Desire Driver: REVOLVE ON! DARKNESS BOOST! X-GEATS! READY! FIGHT!

(Kamen Rider X-Geats)

At that moment, Kagerou was merely a five-year-old child, standing under 1.6 meters tall. However, upon transforming into X-Geats, he instantly assumed the stature of a young man exceeding 1.8 meters in height.

Kasumi: Kagerou?

Mikage's Mother: What the hell are you!?

X-Geats: My name... is... Kamen Rider... X-Geats... A God Killer...

In a moment, X-Geats transported all individuals to a secluded and uninhabited island. Mikage and Kasumi discovered themselves in the company of Miko and Sakura, all of whom were protected within a magnetic sphere that was entirely impervious to any type of damage. Although the sphere was securely closed, a continuous supply of fresh air circulated within it.

Although Mikage was certain in his heart that the armored figure standing before him was indeed his son, he could not dismiss a disquieting feeling that this was not the Kagerou he had known. Deep within, he felt a profound wave of hostility radiating from Kagerou, which was remarkable considering he was only five years old. The figure's helmeted visage revealed purple eyes that shone with a menacing light, and X-Geats launched a powerful assault, skillfully wielding his dual swords to generate two crescent-shaped arcs charged with a vivid deep blue energy, aimed at the two individuals he regarded as foes.

X-Geats: Mikadzuki Jūji Giri! (Crescent Cross Slash)

Although temporarily impeded, X-Geats displayed no inclination towards mercy or restraint. Instead, he unleashed a barrage of slashes that transformed into radiant energy wheels, hurtling toward his adversaries. In response, Mikage's father quickly opened a protective force field, intending to intercept and neutralize the approaching projectiles. However, this defensive action proved to be a mere deception. Almost instantaneously, X-Geats circumvented the barrier and penetrated the force field, where he unleashed a powerful fist of black fire directed at Mikage's father. The force of the blow sent him crashing into a nearby coconut tree, creating a striking spectacle. Reacting instinctively, Mikage's mother surged forward, launching a dark energy sphere in defense. Yet, X-Geats remained unnervingly silent, methodically pulling the Boost Charger from his Geats Buster X. Without uttering a single word, he retaliated by firing a blistering black sphere of flame directly at her, exemplifying his unyielding resolve.

(Geats Buster X Blade Mode)

Geats Buster X: BOOST TIME! BOOST TACTICAL VICTORY!

At that moment, X-Geats was only five years old, yet the energy bullet's impact upon hitting the adversary created shockwaves that reverberated across the entire island. This powerful collision agitated the ocean, resulting in unrelenting waves crashing against the coastline. Just moments prior, the night sky had been calm, bathed in the light of the moon and stars, but it quickly morphed into a chaotic tableau filled with foreboding storm clouds. In an instant, heavy rain began to fall, accompanied by brilliant blue lightning that intermittently illuminated the terrain. The thunder resonated with a force that shook the heavens, prompting nearby vessels to navigate away from the now perilous island.

Kasumi: "Yells" SON! WAKE UP!

X-Geats: Say your last farewell...

Desire Driver: X-GEATS STRIKE! 

X-Geats: Tenshi... no... Horobi! (Calamity Angel)

Drawing upon the full extent of his pent-up anger rooted in profound resentment, X-Geats launched himself into the air, delivering a formidable right kick directed at his opponent. The impact of his strike generated a massive explosion, shrouding the surroundings for those within the protective barrier. As the dust began to clear, Mikage glimpsed X-Geats, who seemed composed and unaffected, standing among the remnants of his adversaries, now nothing more than ashes.

Rising gradually to his feet, X-Geats focused his gaze on his family—his parents and his two younger sisters. With a firm gesture, he broke the energy barrier that had enveloped and protected them, subsequently guiding them all safely back to their home.

Young Miko+Young Sakura: "Scared" Ani-chan...

X-Geats: It's alright... no one... can ever... harm us... once again... 

The violet radiance that had once brightened the helmet slowly faded, prompting X-Geats to return to his true identity as Kagerou. In a fleeting moment, he transformed from the adult persona he had embodied moments earlier into a small child of only five years, resembling a young boy on the brink of growth. Nevertheless, the overwhelming pressure from the extraordinary power he had just encountered proved too much for him, resulting in Kagerou collapsing to the ground, where he lost consciousness.

---------------(End Of Remembrance)---------------

At this moment, Kirigami grasped the underlying significance of Kagerou's perception of himself in Kirigami. They were both Kamen Riders, each harbored concealed histories, and both bore the weight of having their hands tainted by the blood of their adversaries.

Kagerou: "Laughs" Ironic, huh? The World's No. 3 Hero... once killed his own blood.

Kirigami: "Laughs" Really ironic... But... that makes us. Use the painful past to forge the will to move forward to a bright future.

Kagerou: "Laughs" I swear that if you stay in your base mode from the beginning, everyone will think we are father and son.

Kirigami: "Laughs" But we are.

Both Riders gave a slight smile, not noticing Ei hiding behind the room's door.

Ei: "Thought" Aw... finally you have opened your heart, my little fox. And you too, Kirigami.

See you at: Volume 26: Rescue Training And The Final Exam