I was Thrown into an Unfamiliar Manga

A no-holds-barred brawl began the instant their fists collided with each other’s faces.
When Yu-seong hit Ivan in the jaw, Ivan responded with a punch to the nose. When Yu-seong struck the shoulder, Ivan retaliated with a kick to the shin.

Even though the two of them were fighting at extreme close range, neither retreated an inch—they only thought about attacking, blocking, and hitting each other’s bodies.
If an ordinary person had taken even one of the dozens of hits exchanged so far, they would’ve been rushed straight to the ICU.
But both of them possessed ideal muscles that combined elasticity and density, as well as incomprehensibly strong durability. Even after being hit by that kind of barrage, they continued to move as if nothing happened.

“Kuhahaha! You’re holding out well, boy! Then try this one next!”
Suddenly, Ivan’s aura shifted as he faced Kim Yu-seong.
‘Медведь императора’
The Emperor’s Bear.

Yu-seong’s eyes widened in shock as Ivan’s fist struck him.
But Ivan paid no mind and unleashed a fierce flurry of strikes.
The momentary punch power of a brown bear reaches nearly one ton.

A human can’t replicate that ✪ Nоvеlіgһt ✪ (Official version) perfectly due to physiological limits, but with enough muscle mass and weight, it could be approximated.
Yu-seong, who had been trying to endure the fight by taking hits, changed his mind after being struck once. He chose to dodge instead of block.
Naturally, the dynamics of the fight changed.

Now it was a fight between one who sought to land a hit and one who refused to get hit.
But no one can dodge forever—and Yu-seong was no exception.
“Gahk!”

A feint caught him off guard, and a punch slammed into his solar plexus. The pain was so intense he couldn’t even breathe.
He gritted his teeth and tried to shove Ivan away, but the man stood there unmoving—like a boulder.
Compared to Boris, the man he fought earlier that day, Ivan was fundamentally different.

He was, quite literally, the strongest.
But just when Yu-seong, refusing to give in to despair, was about to throw another punch at Ivan’s face—
“Stop! Stop it!”
Sasha, who had been watching silently until now, suddenly rushed in between them.

***
How did it come to this?
Sasha thought as she looked up at the blue-haired man standing before her.

Ivan Vladimirovich Romanov.
One of the world’s strongest fighters—and her biological father.
At first, this had just been a normal runaway.

Then she’d happened to meet Kim Yu-seong.
Because she’d hired him as a one-day bodyguard, she managed to finish her sightseeing in Akihabara without being dragged away by Boris, the head of security.
She had fun, and he’d even shown her some care along the way. Feeling grateful, she had apologized for lying and intended to end their one-day bond on good terms.

But everything changed when her father suddenly showed up in a helicopter.
Yu-seong had only been dragged into this because of her lie.
And yet, her father tested him, and for some reason took a liking to him—going so far as to scout him as a scholarship candidate for the EE Foundation.

The situation had snowballed too quickly for her to intervene. While she was left stammering, the two had already begun fighting.
So now, before it went too far, she stepped in between them.
“Papa, stop. You’ve already fought enough.”

When Sasha said that, looking up at him, Ivan—still caught up in the thrill of battle—ordered coldly:
“Step aside, Sasha. My conversation with the boy isn’t finished yet.”
“If Papa won’t step back, then I won’t either.”

Ivan’s brow twitched in irritation, and he muttered in a low growl:
“…All of you, this one and that one, instead of obediently answering ‘yes’ when an adult speaks…”
And then, he even laid hands on his own daughter.

“Kyaa!”
He grabbed Sasha by the scruff of her neck and tossed her like luggage.
Thankfully, she landed in a patch of soft bushes in the park and wasn’t badly hurt—but now, Yu-seong and Ivan were once again facing off one-on-one.

Already worn to the limit from the extended fight, Yu-seong asked in a cracked voice:
“…You’d lash out at your own daughter just for interrupting your fight?”
Ivan let out a huh and replied with a chuckle:

“They say lions throw their cubs off steep cliffs to make them stronger. Sasha may look delicate on the outside, but she has my blood. That much won’t even leave a scratch.”
Then, looking down at Kim Yu-seong, Ivan said:
“I’ll ask one last time. Serve under me, boy. I’ll give you the power to rule the world.”

Yu-seong looked up at Ivan, his gaze blazing, and answered:
“I refuse.”
“A pity.”

The moment Ivan said that and raised his right fist—
PAPAPAK!
A massive shuriken flew in from somewhere and embedded itself at his feet.

“Hm?”
Ivan recognized that shuriken immediately.
No, there was no way he could forget it.

Because it was one of the cherished weapons frequently used by the very man Ivan had been searching so desperately for.
To use it right in front of him was no different than a blatant provocation.
“Who goes there?! Show yourself!”

Ivan, who had been about to crush Kim Yu-seong’s windpipe, looked around and shouted.
In a flash of light, a black-clad ninja darted in and slashed at him with a ninja sword.
“Kuh!”

Blood sprayed into the air.
For the first time since arriving here, Ivan was wounded. He staggered backward, and a kunoichi with dark violet hair—her face covered in a black mask—stood protectively in front of the barely-standing Yu-seong.

“Acting Head of the 17th Generation Fuma Ninja Clan, Fuma Yukika. Now appearing.”
Caught off guard by the sudden ninja intrusion, Sasha—who had managed to sit up from the soft bushes—gasped in admiration as her eyes sparkled.
Ninjas from Japanese anime… really exist!

***
I was speechless.
Because the person who appeared before me was someone I never expected would come to save me.

Our first meeting had been random—during a dojo challenge match. After that, she openly stalked me and even started showing up at my gym.
And now, Fuma Yukika was standing in front of me, clad in black ninja garb.
She held her sword out in front of her, keeping an eye on Sasha’s father, and glanced back to ask:

“Are you alright, Kim Yu-seong?”
“Senpai… what are you doing here?”
“That Fuma Kotaro guy he’s looking for—he’s my father. He left the village ten years ago, and we lost contact.”

After briefly explaining that, she added that this wasn’t the time for small talk.
“I was trying not to interfere. But that man really did intend to kill you. I couldn’t just stand by and watch.”
As she said that, she pulled something out and handed it to me.

Two pills—one black, one red.
“This black one is a Fuma-style special rations pill. It boosts your body’s natural healing, so as long as it’s not a fatal injury, you should be able to move. The red one is the Oni Pill. It forcefully stimulates your dormant ki, letting you use strength you normally can’t access. It has some side effects, but you should be fine.”
I took the black pill first and swallowed it. Seeing that, Fuma-senpai let out a short heh and smiled, then turned back to Sasha’s father and raised her ninja sword.

“While he recovers, I’ll fight you. Ivan Romanov.”
Then Sasha’s father—called Ivan—burst into laughter.
“I’ve heard of you! They said that Black Yasha bastard had a grown daughter! So it was you!”

Spreading his arms wide, he shouted joyfully:
“Fine! I don’t know what your little scheme is, but bring it on! Let’s see what the Fuma-style assassination sword can do!”
The moment he finished speaking, Fuma-senpai dashed forward at a speed too fast to see.

Fast!
It was an absurd level of speed.
Her body moved like a streak of lightning, dancing around Ivan in a dizzying pattern.

It was as if she had used a cloning technique.
Shhk!
Silent, invisible assassination strikes.

Ivan’s iron-like skin split in multiple places, and blood streamed from his body.
But laughing maniacally, Ivan suddenly reached out and grabbed something with a snap.
“Kuh!”

It was Fuma-senpai.
“You’re quick on your feet—but not as quick as your father!”
He slammed her into the ground without hesitation, gripping her like a bear grabbing prey.

KWAANG!!
A massive cloud of dust rose, and the earth shook as if from an earthquake.
“Hm?”

But as the dust cleared, what remained wasn’t Fuma-senpai—it was a ninja-shaped decoy doll.
“Ninja art—Shedding Technique.”
Reappearing beside me, Fuma-senpai calmly explained, then glanced at me.

“Looks like your wounds have mostly healed. Now take the Oni Pill.”
“You said it had side effects. What kind?”
“It forcibly wrings out every last bit of your ki, so you’ll probably feel weak for a few days. Once your energy recovers, you’ll return to normal.”

“If that’s all…”
As long as it wasn’t something like hair loss or erectile dysfunction, I could deal with it.
Gulp—

The moment the red pill slid down my throat, I realized something was wrong.
It’s hot!
As if I had swallowed fire, my body instantly began to burn.

My heart pounded wildly, like a broken engine.
Panicked, I turned to Fuma-senpai and asked if something was wrong, but she told me it was normal and to endure it a bit longer.
And then—

“HAAAAAAAH!!”
Unable to stand the heat surging through my body, I roared and tore off the black T-shirt covering my upper body with my bare hands.