Demon King’s daughter

"Now, what should I do…?" 

I'm currently staring at a large bag on my bed. 

Well, to be precise, it's not the bag but the long black-haired girl inside it, sleeping soundly. 

For some reason, she's naked—probably because of passing through the Gate of Another World. 

Her large chest sways with every breath she takes. 

Hmm, what a blessed sight right after returning home! 

Truly a feast for the eyes! 

Gulp… 

She's sleeping so soundly… maybe just a little… 

As I reach out toward her swaying chest—our eyes meet. 

"I-I haven't done anything yet! I was just checking to see if you were okay!" 

Even I can tell that's a lame excuse. 

Then, the black-haired girl— 

"Kyaaaaaaaah!!!!" 

Thud! 

Her punch lands perfectly on my face. 

It hurts so much! 

Where does such a slender girl get this much power!? 

Is it because she's the Demon King's daughter!? 

Is that it!? 

"Why am I naked!? Don't tell me…!?" 

She hides her body with the bedsheet while interrogating me, who's crouching and holding my face. 

Well, waking up naked with a guy in front of you would naturally lead to this reaction! 

But please, stop making such a fuss! 

My parents are in this house! 

If this gets any louder, they'll come here! 

If that happens, things will get even more complicated! 

I have to do something! 

"Wait! Please calm down! I really didn't do anything!" 

She looks at me with suspicious eyes. 

"…Really?" 

"Of course!" 

"…Then, where are my clothes? I was wearing them, right?" 

"Probably, they fell off when we passed through the gate. I used Rengan Keikikou to synchronize my clothes with my energy, but I completely forgot about yours…" 

"…I see. I'll believe you." 

She still looks like she wants to say something, but she's calmed down for now. 

For a moment, I thought things were going to get out of hand, but this is good enough for now. 

"Anyway, let's introduce ourselves. I'm Hyoudou Issei. You can call me Issei. I'm the Red Dragon Emperor, and in your world, I'm called the Hero." 

"…My name is Miyu. I'm the only daughter of the Demon King Sirius, whom you defeated." 

"I see. Nice to meet you, Miyu." 

I hold out my hand for a handshake, and Miyu looks a bit surprised but eventually responds. 

"…Yeah. Nice to meet you, Issei." 

It's a bit stiff, but that's understandable. 

After all, I defeated her father in front of her… 

Miyu speaks up. 

"Hey, Issei." 

"Huh? What is it? If there's anything I can do, I'll help." 

"Do you have anything I can wear?" 

"Ah…" 

That's right, I completely forgot. 

Right now, Miyu is wrapped in a bedsheet, but underneath, she's completely naked! 

Well, she's cute and has a great chest—perfect! 

She notices me looking at her body and hides herself further with the bedsheet. 

"Hey, you were looking just now, weren't you?" 

"Ugh… Sorry, I was." 

"Can you hurry up and get me something to wear?" 

She smiles at me, but her eyes aren't smiling. 

She's even leaking magical energy! 

"Yes! I'll get it right away!" 

I frantically search for clothes Miyu can wear. 

---

"Hmm, it's a bit tight around the chest…" 

What I brought her was my own tracksuit. 

I couldn't exactly take my mom's clothes, so after some thought, I chose my tracksuit. 

Well, if I were caught rummaging through my mom's clothes, it wouldn't be funny. 

I thought a men's tracksuit would work, but the zipper on the jacket won't go all the way up and stops around the middle of her chest. 

I underestimated it because it's just a tracksuit, but this is actually pretty erotic. 

"Hey, you've got a nosebleed. Are you okay?" 

"Huh?" 

Oh, it's true. 

I'll stuff some tissue in there for now. 

"So, Miyu, about the future… I think we should tell my parents about you first." 

"Your parents? Are you sure that's okay?" 

"I don't know. Honestly, if I tell them I went to another world and brought back the Demon King's daughter, they probably won't believe me. But I think this is the best option for your future." 

"My future…" 

"I think you'd hate living with the man who defeated your father. But can you bear with it? Just for now, until your life stabilizes." 

Normally, I'd be her enemy. 

Living with someone like that would be unthinkable. 

But Miyu shook her head and smiled gently. 

"It's okay. You… you did defeat my father, but you didn't take his life. You don't just look at the surface—you see the essence of a person. That's why my father entrusted me to you." 

"But Sirius…" 

"My father died because he took responsibility for the war. Even I understand that. And you were trying to persuade him until the very end, right? I knew then… no, I already knew you were a very kind person." 

…I didn't expect her to think of me that way. 

It's true that I defeated Miyu's father, Sirius, but I didn't kill him. 

However, the fact that he died because he lost to me is undeniable. 

That's why I thought she'd resent me. 

But there's no lie in Miyu's eyes. 

I can tell she's being completely sincere. 

"And even now, you regret not being able to save my father more than I do. That's why I don't resent you at all. I believe in you, Issei." 

Miyu is so strong… 

Honestly, her mental strength is something I can't even come close to. 

Miyu says she believes in me. 

Then, there's only one thing I should do. 

"I swear to Miyu and Sirius! From now on, no matter what happens, I'll protect Miyu! Absolutely!" 

I'll protect her no matter what. I decided that the moment Sirius entrusted her to me. 

But now, I've reaffirmed my resolve. 

Hearing my vow, Miyu smiles brightly at me. 

"Yeah!" 

-------

The Next Morning 

Today is Saturday, so my dad is off work.

I'm heading to the living room to tell my parents about Miyu.

Honestly, they probably won't believe me. 

But Miyu's future is at stake. 

I'll make it work! 

"Good morning, Dad, Mom." 

"You're up early for once. You're usually much later… Huh? Issei, did you grow a lot taller? Hey, Dad." 

"Yeah… about ten centimeters? Did you grow that much in one day?" 

It seems they've noticed the changes in my body. 

Even though three years passed in the other world, only a moment passed here. But my body has changed over those three years. 

So, from my parents' perspective, I've suddenly grown taller and more muscular in a single day. 

Mom says, 

"That's impossible! I saw a TV show about someone who grew taller due to a hormone disorder, but could it be…?" 

"Could it be a serious illness!? Mom, let's go to the hospital right now! Is there a hospital open at this time?" 

"There's one nearby that opens at ten!" 

"Alright, Issei's insurance card and wallet!" 

This is bad, the conversation is going in a weird direction! 

They think I'm sick! 

I'm perfectly healthy! 

I have to stop this now! 

"Wait, both of you! This isn't an illness!" 

"What are you talking about!? If it's not an illness, how could you grow this much in one day!?" 

"Please, just listen to meeeeeeeee!" 

---

After ten minutes of calming them down, I sit facing my parents. 

"So, you're really not sick?" 

"Yeah, I'm perfectly healthy." 

Mom still looks worried. 

Well, if you didn't know the circumstances, anyone would think it's an illness. 

"So, what's this important thing you wanted to talk about, Issei? You're so serious. It must be something really important, right?" 

"Yeah, actually…" 

I tell them everything. 

About being transported to another world. 

About fighting the Demon King. 

About bringing Miyu back with me. 

If you were told something like this, you'd normally be dumbfounded. 

But seeing my serious expression, they listen carefully. 

Well, the changes in my height and body probably helped them take it seriously. 

"Transported to another world, huh? Mom can't believe something so game-like." 

"Me neither." 

Well, that's the expected reaction. 

How can I make them believe me? 

Then, Ddraig, who's inside me, speaks up. 

'Partner, why don't you show them the gauntlet? If they see it with their own eyes, they'll have to believe you.' 

That's right, that's an option! 

Nice one, Ddraig! 

"Boosted Gear!!" 

I summon the gauntlet onto my left arm right in front of them. 

According to Ddraig, this Sacred Gear exists in this world too, so it should be enough to convince them. 

My parents are just ordinary people with no connection to fantasy, after all. 

Seeing the gauntlet suddenly appear on my arm, they're shocked beyond belief. 

"W-what is that!?" 

"Where did that come from!?" 

"This is one of the Sacred Gears I possess, called the Boosted Gear. Ddraig, go ahead." 

'Nice to meet you. My name is Ddraig. I'm the Red Dragon Emperor, once known as the Dragon King.' 

""The gauntlet is talking!?"" 

'You two, I know it's hard to believe my partner's story, but it's all true.' 

""..."" 

Ah, they're completely speechless. 

"Well, that's how it is. …Dad? Mom?" 

""..."" 

No response! 

They're completely stunned! 

Come back to reality!! 

"M-Mom…" 

"W-what?" 

"Sorry, but could you get me some tea…? My throat's dry." 

"Y-yes…" 

They're trying to escape reality!? 

Ddraig, what should I do!? 

'No idea.' 

The response from my partner is cold.