The last thing I remember was the blinding glare of truck headlights. Standard isekai prelude, right? Except, instead of meeting a benevolent goddess or a surly god, there was… nothing. Just a vast, echoing emptiness that felt less like death and more like being permanently stuck on hold.

Then, a voice. Not booming or divine, more like a poorly amplified YouTube tutorial.

"Query: Compatible vessel located. Probability of catastrophic system failure: High. Mitigation protocols… insufficient. Initiating forced integration."

And then boom. Not the truck kind. This was an explosion of pure… stuff. Light, energy, raw power slammed into me, filling every empty space, re-writing my very being. It felt like being microwaved from the inside while simultaneously solving the Riemann Hypothesis. And succeeding.

I woke up.

Not in a hospital, not in a picturesque fantasy village, and definitely not in a harem staffed by catgirls. I was in my own bed. Or rather, a bed. It wasn't mine. The room was unfamiliar, filled with the sort of generic, slightly-too-clean furniture you find in student housing. Sunlight streamed through a window, illuminating dust motes dancing in the air. Disorienting doesn't even begin to cover it.

I sat up, head throbbing. That's when I caught sight of myself in the mirrored closet door.

Okay… wow.

I was… different. Still recognizably me – Hadrian – but… better. Sharper features, eyes that held an unnerving intensity, and a physique that screamed "gym membership I couldn't afford." I flexed a bicep, half expecting it to rip my pajama sleeve. It didn't, but I definitely felt… strong.

This wasn't just a generic "better body" isekai upgrade. This felt… fundamentally altered. Like the very core of my being had been replaced with a high-performance engine running on a fuel I didn't even know existed.

And that's when the memories hit me.

Not my old, pathetic memories of ramen-fueled all-nighters playing MMORPGs and awkward attempts at online dating. These were… other memories. Flashes of golden light, cosmic battles, a power so vast it threatened to unravel reality. These weren't my memories. These were… his.

The Sentry.

Robert Reynolds. A hero of near-godlike power in the Marvel universe. A character I knew intimately from comics, a character whose immense abilities were forever shackled to an equally immense, self-destructive darkness.

And somehow, impossibly, I was him. Or, rather, I was me, Hadrian, burdened with his power. This "forced integration" felt less like a power-up and more like a cosmic Trojan horse.

My head swam. This was too much. Way too much. I needed information. I needed context. I needed… Google.

I stumbled out of bed, searching for a phone, a laptop, anything to anchor me to reality. I found a smartphone on the nightstand, unlocked and displaying a home screen I didn't recognize. After navigating the Japanese language settings (thank god for years of watching unsubbed anime), I fired up the internet.

"Kouh Academy."

"Occult Research Club."

"Devils."

"Angels."

"Fallen Angels."

Highschool DxD. Holy crap.

The pieces clicked into place. I was in that world. That ridiculously over-the-top anime world where busty demon girls battled angels and the protagonist leveled up by groping them. My life had gone from zero to unbelievably absurd in a matter of minutes.

Panic threatened to overwhelm me. Jason, the introverted otaku, dropped into the middle of a supernatural power struggle armed with the power of the Sentry. I was a walking, talking, potentially reality-warping disaster waiting to happen.

The Sentry's memories continued to flood my mind, fragments of his battles, his fears, his crippling self-doubt. The Void, his dark counterpart, whispered insidious promises of control and power. This wasn't just an isekai adventure; it was a mental battle for dominance.

I took a deep breath, trying to center myself. Okay, Jason. You've spent years strategizing in RPGs, min-maxing characters, and reading power-scaling forums. Time to put those useless skills to the test.

First: Information. I needed to understand the current situation, the factions, the players. Knowledge was power, especially when you're carrying around enough raw power to level a city.

Second: Control. I had to get a handle on the Sentry's abilities. Manifesting golden energy and flying around was cool in theory, but I needed to learn to modulate it, to focus it, to prevent it from accidentally turning the entire school into a crater.

Third: Don't. Die. Simple, right? Given my track record in life, probably not.

I spent the next few hours immersing myself in the memories i had of the world of Highschool DxD. Character bios, power levels, plot summaries – I remembered it all. I rememebered about Rias Gremory, the crimson-haired heiress of a powerful devil clan, and her peerage. I remembered about Issei Hyoudou, the perverted protagonist with the boosted gear. I remembered about the angels, the fallen angels, and the complex political landscape of the supernatural world.

The information overload was intense, but it was also oddly comforting. It gave me a framework, a set of rules to play by. And rules, however absurd, were something I understood.

As the day wore on, I began to experiment with the Sentry's power. Tentatively at first, I focused on the feeling, the energy that thrummed beneath my skin. I tried to manifest it, to shape it, to control it.

The results were… mixed.

I managed to levitate a pen a few inches off the table before nearly setting the curtains on fire. I accidentally shattered a drinking glass with a casual flick of my wrist. I conjured a faint golden aura that made me feel like I could bench-press a truck, but also gave me a splitting headache.

It was like learning to ride a bike while simultaneously juggling chainsaws.

And then, the Void whispered again. A seductive voice promising ease, control, absolute power. Just let go, it urged. Surrender to the darkness.

I pushed it back, focusing on the image of my old room, my old life. The countless hours spent lost in fantasy, the comfortable anonymity of being a nobody. It wasn't much, but it was mine. And I wasn't about to let some cosmic parasite take it away.

As dusk settled, a knock on the door jolted me back to reality. I froze, my heart pounding. Who knew I was here?

"Jason-san? Are you ready? Its time for school."

I took a deep breath, trying to project an air of confidence I definitely didn't feel. "Coming," I called out, forcing my voice to remain steady.

I glanced at myself in the mirror. The eyes staring back at me were still unnervingly intense, but now they held a flicker of something else: a strange, hesitant hope.

Jason, the lonely otaku, was dead. But maybe, just maybe, with a little luck (and a whole lot of cosmic power), I could survive this. Maybe I could even… thrive.

As I opened the door and stepped out into the unfamiliar hallway, the Void whispered again, a constant reminder of the darkness within. But this time, I didn't try to push it away. I acknowledged it, accepted it as a part of me.

Because I knew, deep down, that in this insane world of devils and angels, I would need every advantage I could get. Even if that advantage came with a price.

The journey had begun, and Jason Reynolds, the Sentry, was ready to play. Or at least, he was going to try like hell.