Reincarnated in the World of High School DxD

"Kazuki!!"

The deafening roar of an explosion drowned out Rias's anguished scream.

Riser's attack had obliterated a diagonal section of the new school building, leaving a molten, smoldering ruin behind.

The acrid stench of scorched debris filled the air as Riser descended onto the rooftop, his expression smug with satisfaction.

"Hah... hah... serves you right. This is what happens when you dare to anger me!"

Panting heavily, Riser's words came across as excuses to his sister Ravel, almost as if he was trying to justify his actions.

"Brother, don't you think you've gone too far?"

"What nonsense, Ravel. This was nothing more than an accident during the game, just an unfortunate incident."

Ravel's frown deepened at her brother's cavalier dismissal. However, she knew there was no undoing what had been done.

The sheer power of Riser's magical attack would have left nothing behind, not even bones.

'He was an intriguing person... such a shame.' A tinge of regret flickered in Ravel's heart.

She had wished to speak with Kazuki a little more, but now she could only turn her gaze to the grieving Rias.

"Kazuki… no... Not like this..."

Rias clenched her trembling fists, guilt and anger boiling within her. She had already lost Kazuki once because of her own oversight, a classmate who had died protecting her.

Kazuki wasn't someone who stood out in class, yet whenever someone was in trouble, he was the first to lend a helping hand. Rias had so many unanswered questions about him—his gentle demeanor, his incredible martial skills.

And then there was the day she opened her heart to him, confessing her feelings about marriage and her reluctance toward her engagement, he was the second one to know after Akeno, Kazuki had laughed, but he hadn't dismissed her feelings.

Instead, he'd told her to stand firm for what she truly wanted. The warmth she felt at that moment was unlike anything she'd ever experienced before.

'If I had more time with him... would I have understood what this feeling truly was?'

But it was too late now.

Kazuki Fuwa had vanished into the flames, leaving her with an emptiness that consumed her. A surge of unprecedented rage began to well up within her.

"How dare you... How dare you take Kazuki—my precious one—from me!"

As Rias prepared to unleash her fury, her magic beginning to crackle and surge, a heavy sound interrupted her.

Thud.

The sound of something landing nearby caused her to snap her head up.

The shocked expressions on Riser and Ravel's faces drew her attention. She turned to see what had stunned them so thoroughly, and her own expression mirrored theirs.

"What the—?!"

Standing before them was a monstrous figure.

A crimson-clad demon god stood tall, its body armored in an otherworldly exoskeleton.

Protrusions resembling horns jutted from its head, while a shimmering medallion embedded in its forehead reflected the moonlight. The armor was not merely metallic but disturbingly organic, like the carapace of a beetle fused with flesh. Its joints, covered in strange, pulsating cells, gave it an unsettlingly lifelike appearance.

The crimson demon god stared at Rias" with unwavering focus, and despite its terrifying visage, she felt something familiar—a strange warmth emanating from its gaze.

A name came to her lips unbidden.

"...Kazuki?" she mumbled.

The armored figure seemed to smile, its alien mouth curling faintly.

"You figured it out quickly, Buchou."

The voice was unmistakable. It was Kazuki Fuwa's.

"Kazuki!!" Rias didn't hesitate; she threw herself into his arms, tears streaming down her face.

"I'm so glad you're safe! But... what is this form?"

"This... is the power of my Sacred Gear—you could call it a kind of armor," he replied, his voice steady.

"Your Sacred Gear?"

"I'll explain everything after I take care of that bastard. For now, you need to step back."

"Alright... be careful, Kazuki."

Reluctantly, Rias let him go, her gaze lingering on him as he turned to face Riser.

"Sorry to keep you waiting, Riser. Ready for round two?"

"You... How the hell are you alive?!"

"Your flames weren't enough to burn through the Bio-Boosted Armor—the true power of the Guyver."

"Guyver? Is that the name of your Sacred Gear?"

"Knowing its name won't change your fate."

Before Riser could react, a blinding beam shot from the medallion on Kazuki's forehead, piercing straight through Riser's skull.

"Ughh!?"

Riser's body crumpled to the ground, only to be consumed by flames as his regenerative powers began to work.

"Damn it... What the fuck was that?!"

Riser staggered to his feet, confusion and anger evident on his face. Kazuki—no, Guyver—stood silently, his crimson form glowing ominously in the moonlight.

He wasn't done yet.

"Being immortal sure is convenient. It means I get to kill you… as many times as I like."

"Wha—?!"

Kazuki's voice thundered, rage laced within his words. "For my comrades, I'm going to make you pay, Riser! Every single one of them!"

In an instant, Kazuki closed the distance between them, activating the gravitational control orb embedded in his waist.

"SMASSH" His fist, cloaked in intense gravitational energy, crashed toward Riser with devastating force…

—Gravity Knuckle.

"This is for Koneko!"

Boom!

The blow sent Riser reeling, his body disintegrating into flames before regenerating once more.

"Damn you!"

Kazuki's armored form shifted as he extended the blades protruding from his arms.

The hum of vibrating energy filled the air as the High-Frequency Swords came to life.

"This one's for Akeno!"

The blades carved cleanly through Riser's arms, severing them in an instant.

"AAAAAAHHH!!" Riser's scream echoed as he collapsed, his arms re-growing amidst his Phenex flames.

Yet, the once unstoppable fire appeared to flicker, its intensity beginning to wane.

Kazuki advanced again, his gravitational control orb glowing ominously. This time, he unleashed a concentrated beam of energy—Pressure Cannon—obliterating Riser's torso.

"This is for Yumi!"

"Guh—!"

Riser's body collapsed once again, massive holes left in his frame. But even as his flames restored him, they grew weaker, dimmer.

With cold precision, Kazuki raised his head. The medallion embedded in his helmet glowed and from its center, a thin, focused beam shot out—Head Beam.

"This one's for Asia!"

Riser's head was riddled with holes, his body slumping lifelessly before igniting in flames once more. The Phenex's resurrection was slower now, his flames sputtering weakly.

"D-Damn it...!"

Kazuki didn't stop.

He activated his gravitational control orb again, propelling himself into the air. With his legs enveloped in gravitational energy, he came crashing down with a devastating —Gravity Kick.

"This one's for Issei!"

"GAAAAHH!!"

The impact sent Riser flying across the battlefield, his body crumpling upon landing. His flames reignited to heal him, but they were now barely a flicker.

"Ughh" Riser staggered to his feet, trembling. His once-proud wings of flame faltered, and his body swayed as he struggled to stand.

Kazuki, still cloaked in his crimson armor, stood tall, his voice sharp and mocking. "What now, Riser? Do you surrender?"

Those words ignited a final burst of defiance within Riser. With a furious roar, his wings flared up, and he took to the skies.

"I WILL NOT FORGIVE YOU! YOU HEAR ME?! NEVER!!"

Hovering above the battlefield, Riser's mind raced. He couldn't match Kazuki in raw power—his attacks were relentless, his strength monstrous.

However, this wasn't just a fight, it was a Rating Game. Victory didn't require defeating an opponent's strongest piece.

Riser's eyes locked onto the figures behind Kazuki: Rias, standing firm, and Asia, kneeling beside the injured Issei, desperately healing him.

"Yes... That's it," Riser muttered, his voice trembling with malicious glee. "This is a game, after all. And if the King falls, the game is over!"

Channeling every last ounce of his magical energy, Riser summoned a massive inferno, flames larger and brighter than before.

His entire body was engulfed, transforming him into the image of a mythical Phenex reborn.

"Take this, Rias! It's your defeat!!"

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Read early at: [email protected]/SMU_NANI