I was Thrown into an Unfamiliar Manga

We followed Fuma-sunbae’s grandfather into the main building of the estate.
The surrounding scenery was the very definition of a traditional Japanese mansion.
It had that quiet, humble elegance unique to old homes.

Unlike Karen’s house, which had been modernized on the inside, this place seemed to have preserved its old form completely.
As we walked along the creaking wooden corridor, a beautifully arranged indoor garden came into view.
It was man-made, but looked as natural as anything in the wild.

Noticing my gaze linger on the garden, Fuma-sunbae, walking beside me, explained briefly:
“It’s my grandfather’s cherished garden. He’s been tending to it himself since his younger days, so almost every part of it has his touch.”
Just as he looked strict and disciplined on the outside, he seemed equally meticulous when it came to gardening.

You could see the owner’s personality reflected in the way every detail of the garden was arranged.
Eventually, we arrived at a room built with eight tatami mats.
Perhaps to emphasize the beauty of empty space, the wide room had almost no decorations except for a hanging scroll and a vase.

As I awkwardly followed Fuma-sunbae’s grandfather into the room, he turned slightly and asked:
“What would you like to drink?”
Since he was asking me directly, I quickly answered,

“I’ll drink whatever you offer.”
“…Good.”
Nodding slightly, he slowly sat down on a cushion and cleared his throat before glancing between me and Fuma-sunbae.

“Sit down, both of you.”
“Yes, sir.”
Fuma-sunbae and I knelt respectfully on the cushions across from him.
Then, the old man rang a small bell placed beside him, and a middle-aged woman in a brown apron slid open the door and entered.

“Please bring some tea.”
“Yes, Master.”
She bowed deeply, then quietly left the room again. The way she moved was something you’d expect to see in a historical drama.

Once all preparations were complete, Fuma-sunbae’s grandfather finally began to speak.
“I’ve heard much about you—not just from my granddaughter’s letters, but also from many others. Kim Yu-seong.”
He already knew my name, even though I hadn’t introduced myself.

But… many others?
“What do you mean by that?”
“Just what I said. A high schooler who defeated the Destruction God Ivan with his bare hands. It’d be more surprising if word hadn’t spread. And ever since my granddaughter mentioned you in her letter, many of the village elders have grown curious. With your Polar Yang Body, it’s believed you might be able to learn our family’s secret martial art without going through the harsh training process.”
“I didn’t expect you to know that much about me—not just my name.”

“It’s only natural. I’ve personally gathered as much information on you as I could.”
Without batting an eye, he dropped a terrifying statement.
Then he fixed his sharp gaze on me.

“Enough small talk. Let’s get to the point. You asked if there was any way to learn without becoming my granddaughter’s husband, didn’t you?”
“Ah, yes.”
At this point, I’d take any martial art I could get my hands on.

Even though I’d gotten sidetracked here and there, learning more was always a net gain.
“First, I must give you the standard answer. is a highly dangerous martial art developed during the Sengoku period for killing people. I cannot teach something like that to an outsider—not even someone from the village unless they’re part of the bloodline.”
“I understand.”

To be honest, I’d already heard as much from Fuma-sunbae, so I hadn’t expected much.
“But,”
And with that, he presented a new condition.

“Not far from our village, there’s an abandoned Western-style house. A yuki-onna has taken residence there. If you can drive her out, I’ll make an exception and allow you to learn .”
“Grandfather!”
Fuma-sunbae stared at him in shock.

But her grandfather remained expressionless as he looked at me.
Apparently, this little staring contest would only end when I gave an answer.
And since I wasn’t in any position to be picky, I accepted without hesitation.

“Sure. Why not? Let’s do it.”
***
“You idiot!”

On the way out of her grandfather’s room, Fuma-sunbae scolded me harshly.
I looked at her, confused about her sudden outburst, and she said in exasperation:
“The yuki-onna he mentioned is a type of yokai you’re only supposed to encounter in winter. But she’s roaming around in the middle of summer? That’s almost certainly a high-ranking yokai. No matter how rare your Polar Yang Body is, fighting something like that is basically suicide. My grandfather only gave you that condition because he expected you to back down.”

A high-ranking yokai, huh.
I couldn’t really grasp what kind of strength that entailed, so I asked:
“How strong are we talking here?”

Fuma-sunbae sighed and rubbed her forehead like ◆ Nоvеlіgһt ◆ (Only on Nоvеlіgһt) she couldn’t believe me.
“Haah~ You’re probably the only idiot in the world thinking of fighting a great yokai. The scary thing about high-level yokai is that they can think, speak, and act like people. Lower-class yokai are born from human negativity and rumors and move purely on instinct—they’re not that hard to deal with. But a yokai that’s lived hundreds, maybe thousands of years, gaining both power and wisdom, becomes a real threat.”
“Okay… so based on that mask guy from last time, how would you compare them?”

She hesitated for a moment, then replied:
“It would take at least ten of those guys just to maybe hold out against one great yokai.”
“So basically, they’re insanely strong.”

“Exactly.”
I clenched and unclenched my fist.
“Then I definitely can’t back down.”

When fighting humans, I had to be careful not to cause permanent damage. But if the opponent was a yokai? I had no such concerns.
If anything, I wanted to test my limits.
Even though I could feel myself growing stronger by the day, I had nowhere to properly measure it.

“…Fine. If it’s come to this, I’ll help you to the end. If you end up dead because you got cocky, I won’t be able to face your parents.”
“I appreciate that.”
I offered her a polite reply, and she chuckled softly.

“Since we’ve worked off that lunch, I’ll make sure dinner tonight breaks the damn table legs.”
“Whoa!”
Seeing my surprised expression, she smirked and brushed her finger under her nose.

“Look forward to it. My family’s cooking is no joke.”
***
Long story short: she was right.

After taking a quick bath and returning to my room, I found a full meal already set out—and to my surprise, there was even alcohol on the table.
I normally avoid drinking since it nullifies the benefits of training, but I figured, why not? When would I get a chance like this again?
The tipsy warmth I hadn’t felt in a while helped me momentarily forget that I was in a ninja village deep in the mountains.

Still, maybe because Kim Yu-seong’s body has low alcohol tolerance, even a single bottle had my head spinning, so I stopped myself and asked them to clear the table.
Then, to make up for the exhausting day of travel, I decided to go to bed earlier than usual.
I laid out the futon, changed into something comfortable, and flopped onto the floor.

The thick, fluffy cotton blankets made it feel like I’d fall asleep in no time.
There weren’t even fluorescent lights—just a candle for illumination. I blew it out with a fwoosh, letting the room fall into darkness.
The only remaining light came from the moon shining in through the window.

Bathed in silence, I slipped into unconsciousness without realizing I had fallen asleep.
***
Rustle—rustle—

It happened while I was deep in sleep.
I was roused by a faint rustling sound nearby and slowly opened my heavy eyelids.
“……”

Standing beside my futon was Fuma-sunbae, wearing a thin yukata—something I’d never seen her in before.
Startled, I almost sat up… but with supreme willpower, I forced myself to stay still.
I wanted to see what she was doing, sneaking into my room in the middle of the night.

Then—
Fuma-sunbae reached for the sash tied around her yukata.
No way…?

And just as the phrase “no way” crossed my mind, she proved it right.
Without hesitation, she undid the sash.
Shff—

Revealing black underwear and smooth, bare skin.
I hurriedly shut my eyes.
Then I heard her voice, softly muttering at my bedside.

“Kim Yu-seong… you’re awake, aren’t you?”
But I couldn’t say a word.