My Little Sister Suddenly Confessed to Me, but What Am I Supposed to Do by Dating My Little Sister? - Chapter 75 & 76 & 77

Chapter 75: The Strongest Enemy Joins the Fray!!

Read — Hey.

Prez: You’ve got some nerve, “unread-and-ignoring” me.

Read — No, I was just away on a trip to Ishigaki Island…

Prez: Hmph. Must be nice for some people.

Read — Thanks to you…

Prez: Come here for a second. I need to talk to you.

Read — Ah, sorry, that’s impossible.

Prez: I don’t care, just come.

Read — No, it’s truly impossible.

Prez: Fine, then I’ll come to you. Where are you?

Read — Um, on the Shinkansen…

Prez: Huh?

Read — I’m heading to Nagano, so it’s impossible.

Prez: …I am seriously going to get you someday…

I quietly turned off my smartphone while leaving the Student Council President’s last message unread… You probably want to say it doesn’t matter if I turn it off… and you’re right, it doesn’t… Ugh.

“Onii-chan, who are you messaging on LINE?”

“Ah, the President said she wants to talk.”

“Heeeh… when did you two exchange LINE info, Onii-chan?”

“Well, it was kind of forced, in a way…”

My sister and I are currently on the Shinkansen heading toward Nagano Station.

It’s been less than a week since we returned from Ishigaki Island.

For the record, the President’s message came while I was in Ishigaki, but it was too much trouble, so I “unread-ignored” it and completely forgot about it until just now…

“More importantly, where’s Mom?”

What’s the point of going to her parents’ house if she’s not even there?

“This morning, before you woke up, she had to go to the hospital. Apparently, the person who was supposed to cover for her during her vacation ran away. She said she’ll come as soon as she finds a replacement.”

“Seriously? How busy is Mom’s job…? Wait, does that mean at worst, she won’t come at all?”

“Hmm, I don’t know. I feel bad for Mom, but for me, it’s super lucky—a trip alone with Onii-chan~~”

My sister clings to my arm, looks up at me, and softly closes her eyes… No, I’m not doing it.

“Ah, excuse me! Two coffees, please.”

The cart service happened to arrive right next to me, so I ordered coffee. I wanted an ekiben, but apparently, they aren’t selling “Tōge no Kamameshi” right now… Well, ekiben on the Shinkansen feels like it lacks sentiment anyway, so it’s fine, but it’s still a bit disappointing. (I heard they might sell them at Karuizawa stops… I really want kamameshi.)

“Honestly, Onii-chan!!”

She opened her eyes wide and displayed her anger. Ever since that incident in Ishigaki, my sister has been pushing for a kiss every chance she gets. No, I won’t do it. That was a close call; it was truly “tropical magic.”

“Eh? You want to drink this too, right, Shiori?”

I feigned ignorance and handed the coffee to her.

“I’ll drink it, but honestly!”

Ahh… coffee is great…

The Shinkansen passed through Karuizawa and headed straight for Nagano. Did my sister’s mood improve because I held her hand? She began humming while enjoying the mountain scenery and the rural landscapes outside the window.

After transferring at Nagano Station and riding the Shinetsu Main Line and the Shinonoi Line for about an hour, we arrived in Azumino City, Nagano Prefecture.

My mother’s family home is on the opposite side of the river from the station. We could have asked for a ride, but the weather was nice and I wanted to enjoy the cool breeze and scenery by the river. So, my sister and I walked leisurely down the rural road, dragging our carry-on bags.

Taking in the clean air of Azumino as we walked slowly, we eventually arrived at a large Japanese-style house. This is my mother’s family home, where my uncle and aunt live with their daughter and my grandmother.

It has quite a grand gate. I pressed the somewhat mismatched intercom, but there was no reply…

I told them we would arrive today, so they shouldn’t be out. As I went to press it again, I heard a noise from the other side of the gate.

Accompanied by the sound of a lock turning, the door opened, and a small object charged out from inside straight at me.

“YUU-NII-CHAMAAAAA!!!”

Screaming that, and using incredible explosiveness, she latched onto my neck.

I gently caught and held her, then spoke.

“Mitsuki! You’ve been well? It’s been two years. You’ve gotten so cute!”

“Ehhh! I was already cute beforeeee!!”

“That’s true. Very cute, very cute.”

This is my cousin, Yamanoe Mitsuki, who has followed me around like a puppy since she was little. We’re reuniting for the first time in two years.

“M-Mitsuki-chan… it’s been… a while.”

My sister, standing behind me, greeted Mitsuki as if trying to emphasize, I’m here too, you know.

“Ah, Shiori-neechama, you were here?”

“M-Mitsuki-chan, that’s mean…”

“Just kidding! Shiori-neechama looks well too, and she’s gotten even prettier!”

Even as she said that, she stayed latched onto my neck and wouldn’t let go…

“What grade are you in now, Mitsuki?”

“Ehhh, you forgot? I was in second grade when you came before. I’m in fourth grade nowww!”

Is she big for a fourth grader? Well, girls grow up fast. And this girl especially has acted mature since she was little—likely influenced by Grandma—asking me to date her or marry her since kindergarten. Well, she’s in fourth grade now, so I doubt she’d still say those things, but given the example of my sister, I’m a little scared…

“Yuu-niichama, what are we going to play!!”

“Before that, I have to greet Uncle, Aunt, and Grandma. Can you let go for a bit?”

“Ehhh, noooo!”

“Please.”

“Then, will you sleep with Mitsuki tonight?”

“Sure, sure.”

I agreed while patting Mitsuki’s head.

“EH!!!”

Suddenly, my sister let out a loud voice, her face full of shock.

“Hmm?”

“O-Onii-chan… you’re going to sleep with Mitsuki-chan…?”

Eh? Is that not allowed? Is it “out” for a fourth grader? Even if we’re cousins? How does this work?

“Umm… that’s right, Mitsuki has grown up now, hasn’t she?”

“Ehhh! We slept together beforeeee! Fine then! In that case, I’m not letting go until bedtimeeee!”

“Alright, alright, I get it, I can’t breathe… I’ll ask your mom first. Anyway, I have to greet Grandma.”

“Okaaay! Mommy will definitely say it’s fine! Yay! Let’s talk until we fall asleeep!”

Finally, she let go. As I tried to pick up the luggage she’d knocked over in her excitement, I caught my sister muttering something in a small voice.

“…Onii-chan… as I thought… even in that magazine… Shirai-sensei… loli… that’s why I… even a kiss…”

My sister has gone past “yandere”… she’s “sick” again…

Chapter 76: The Strongest Enemy Joins the Fray!!

Guided by Mitsuki, I greeted my aunt. My uncle was apparently away on an urgent business trip; honestly, men never seem to appear in this story. Soon, I might stop appearing too, right?

“Mommy! Yuu-niichama said he’d sleep in my room with me tonight!”

“Oh, how nice. I’ll have to bring an extra futon up later then.”

“Ehhh, we can just sleep together in my bed!”

“If you sleep in Mitsuki’s bed, Yuu-kun will fall off, won’t he?”

Wait, it sounds like I’m the one insisting on sleeping together… Oh no, Shiori is getting even “sicker,” muttering things I can’t even repeat here…

For now, I gave my aunt her greetings and souvenirs before heading to the room where my grandmother was.

“Grandma, I’m coming in!”

I entered without waiting for an answer, knowing this house like the back of my hand. Grandma was in her study, surrounded by a mountain of books, sitting in front of a PC.

People might think a “Grandma” using a PC is strange, but mine is young—not even sixty yet. And she looks even younger; you could say she’s in her forties, maybe even her thirties. A “beautiful witch” type?

I haven’t mentioned it, but my mother is also incredibly young-looking, easily passing for someone in her twenties. Since both Mom and Grandma had children at a young age, their actual ages are low, and the women in our family seem genetically predisposed to look youthful. My dad, however, looks like a normal middle-aged guy.

“Yuu, Shiori, welcome! But I’m not ‘Grandma,’ am I? Did you forget after two years!”

“Ah, sorry, sorry. Yayoi-san.”

“Yayoi-san, we’re here! It’s Shiori!”

Shiori greeted her from behind me. If you call her “Grandma” to her face, she always gets angry and forces you to use her name.

Yamanoe Yayoi—my grandmother. She has a black bob with no gray hair (maybe she dyes it?) and looks like she’s in her thirties. Two years ago, she claimed she got hit on at Matsumoto Station. Seriously…?

And get this: her profession is an author. After my grandfather died before I was even born, she started writing novels and they became huge hits. She’s won those “big” awards—not light novel awards, but the ones you see on the news and TV. My love for books is her influence; she buys tons of them for work and publishers send them to her, so she regularly sends them to me to read.

“So your mother couldn’t make it after all? She really is a flighty child. You and Shiori must have a hard time; it’s my fault for how I raised her. I’m truly sorry.”

“No, no, it’s not your fault, Yayoi-san. I think it’s just Mom’s natural personality.”

“Then isn’t half of it my fault anyway?”

The three of us burst out laughing.

“I’m glad you grew up to be such good kids. When Shiori was born, your mother was so irresponsible I wondered what would happen… Oh, dear, a reminder email from my editor. They’re pestering me to finish by Obon. If you two had come during Obon, I could have spent more time with you. Sorry.”

“No, it’s fine. Even if we came during Obon, Mitsuki would probably just demand I play with her anyway. Sorry for bothering you; good luck with work, Grandma.”

“It’s Yayoi-san!! Well, make yourselves at home. I’ve asked for a feast for dinner.”

“Okay! Thank you, Ba—Yayoi-san.”

We left the study, and Mitsuki was already waiting by the door.

“Yuu-niichama, are you done talking?”

“Yeah. Yayoi-san looks busy.”

“Yeah, Mitsuki doesn’t really get Yayoi-chama’s books. Come on, Niichama, let’s play!”

The immediate demand to play. I’m used to it since it’s an annual tradition.

“Sure. What do you want to do?”

“Hmm, let’s play a game!”

I guess she’s past playing “house.” She used to make me do that all the time—I was always the husband who had to beg for forgiveness for cheating… and Shiori was always the “other woman.”

“Okay. What game?”

“Umm, Othe**o!” (It’s a trademark, so let’s call it the “black-and-white-flipping game”).

“And also, Shogi!” (Like March Comes in Like a Lion or The Ryuo’s Work is Never Done! It’s popular lately. That Fujii-kun is strong; no openings in his early, middle, or late game. Though it’s not popular on web novel sites… everything besides ‘Another World’ fails there, but I won’t lose! I want to show everyone our dynamic spirit…)

“Go!” (Classy. Well, the pro player won the People’s Honour Award along with Habu-san. Incidentally, his ex-wife was a professional shogi player).

“Chess!” (Also classy. Incidentally, Habu-san is also top-class in Japan at chess. I heard it’s just his hobby…)

“Gomoku!” (Nostalgic. You do that at school if there’s graph paper).

“Animal Shogi!” (An introductory version, but surprisingly deep… Wait a minute…)

“Wait, Mitsuki. Why are these all ‘two-player zero-sum finite deterministic complete information games’? Let’s do something for the three of us—”

I turned to see Shiori with teary eyes…

“Ehhhh! But I want to do thooose!”

Is Mitsuki trying to exclude Shiori? Scary… this girl has become scary now that she’s in fourth grade.

“Isn’t there anything else? Rural games usually mean The Game of Life or Donjara, right? Or Daifugō (Great Millionaire)?” (Arguments always break out over whether it’s called Daifugō or Daihinmin, and then the local rules cause even more fights).

“Hmm, I have Geister!” (I think this is also a trademark? A ghost game. If you don’t hide them before putting them on the board, people can tell which is which. And they’re white, so they get dirty easily).

Wait, aren’t these all two-player games…?

“L-let’s play with the three of us. We’ll do a winner-stays-on tournament.”

“Ehhhh.” Mitsuki made no effort to hide her displeasure at Shiori joining.

“M-Mitsuki-chan… are you scared of losing to me? Onii-chan is weak at games, after all.”

Oh boy, she’s ignited Shiori’s competitive fire. It’s true I’m not good at games. I have no one to play them with! Leave me alone!

“I’m strong!”

“I’m pretty good myself!”

“Then, shall we bet Yuu-niichama?”

“Eh? …Bet Onii-chan?”

“We’ll play for the right to be with Yuu-niichama, Shiori-oneechama!!”

“F-fine! Mitsuki-chan, it would be a shame if we came all this way and you ended up all alone. How lonely for you.”

“Same to you, Shiori-neechama! Mitsuki will go on a date with Yuu-niichama, so you can just stay home and watch TV by yourself!”

“Wait, wait, wait, hold on a second—”

“ONII-CHAN, SHUT UP!!”
“ONII-CHAMA, SHUT UP!!”

“Ah… yes ma’am…”

Two-player zero-sum finite deterministic complete information games. Games where luck doesn’t matter and a win or draw is always determined. Wait, didn’t I just fall right into Mitsuki’s trap? (Geister is probably an incomplete information game).

Ignoring my will entirely, the battle between the two was joined!

I mean, why a game all of a sudden?

Chapter 77: The Strongest Enemy Joins the Fray!!

“Checkmateee!”

“Kyahhhhhhhhh!”

The first round: Gomoku. Since it was already close to evening, they chose the simplest game for the showdown—and my sister lost effortlessly. I knew it… she was totally set up…

“Yuu-niichama~~ I get to be with you all day todayyy!”

“Uuuuu, Onii-channnnnnn!”

Man, to think the “invincible” younger sister would be defeated so easily…

“Now then, Shiori-neechama, let’s play for tomorrow’s rights too~~”

The way she has games prepared for the entire week we’re here… she’s so thorough. I can’t believe Shiori didn’t notice that. Or is Mitsuki just that incredible?

“Fine! I won’t lose this time! Watch me, Onii-chan!!”

Ah, I feel like I can see the “defeat flag” being raised already.

“Shiori-neechama can choose the game~~”

Mitsuki spoke with an air of total composure, telling Shiori to pick. But why aren’t they playing video games? We played Mari* Kart before, didn’t we?

While I harbored that simple doubt, Shiori chose Chess.

It’s a minor game in Japan but a globally major mental battle. I see—Mitsuki, knowing how smart Shiori is, wants to show me that she is even smarter… How terrifying.

“I’ll let Shiori-neechama have the first move.”

The game began. Perhaps she’s been studying? Mitsuki skillfully used her Knights to set up a double-attack on the Rook and Bishop. Sh-she’s strong. Is she really in 4th grade?

“I won’t lose! I won’t let you take Onii-chan! I’ll protect him!!”

My sister resisted desperately, using her Queen to firmly guard the King. Wait, Shiori, when did you even learn Chess…? Well, she has a ton of friends; I guess it’s no surprise she knows someone who plays…

In Shogi, losing your major pieces like that is fatal, but in Chess, you can’t use the pieces you’ve captured, so you can still fight. However, the difference in strength was large. Mitsuki took out the keystone of the defense: the Queen.

“Check, Shiori-neechama!”

Mitsuki stripped away the Queen and put the King in check.

However, Shiori skillfully moved the King out of harm’s way, promoted a Pawn (becoming any piece she wanted), revived her Queen, and put Mitsuki in check.

“I will absolutely never let you take Onii-chan!”

Visualizing me as the King and herself as the Queen, Shiori’s counterattack gained momentum.

“Kh!”

For the first time, a look of agony crossed Mitsuki’s face.

And then…

“It’s… a Stalemate…”

After a brutal exchange of moves where both sides were stripped of almost all their pieces, Mitsuki declared a draw. Unlike Shogi, Chess is a game where draws are common, especially at top levels where players are evenly matched.

“Haahhhhhh…”

Since she had been in a disadvantageous position, Shiori let out a sigh of relief. I mean, what is this? Isn’t this supposed to be a romantic comedy?

“……”

“……”

The two of them stared at the board in silence… Are they really that serious…?

“Well then, let’s all play together tomorrow,” I suggested, trying to break the tension.

“I-I suppose that’s fine. We didn’t propose a tie-breaker, and it was a good game, Shiori-neechama.”

“Y-yeah. You were amazing, Mitsuki-chan. If I hadn’t had the first move, I would have lost.”

The two of them shook hands. Hey, what on earth is this…?

“Heeey, sorry to interrupt while you’re having funrr, but dinner is almost readyrr. We’re having sushiii, so go take your baths firstrr!”

My aunt came into the living room and declared the end of the games.

“Shiori-neechama, the rest will have to wait until tomorrow.”

“Yeah! I’ll win next time!”

The two of them stared at each other, their fighting spirits palpable. Seriously, what is this…?

Then, Mitsuki turned to me and said something outrageous!!

“Now then, Niichama, let’s take a bath together.”

“Huh?”

“Eh?”

Shiori and I spoke at the exact same time.

“No, no, no, no, no.”

“M-Mitsuki-chan, that’s…”

Mitsuki looked at Shiori with a face that said What are you talking about? and spoke.

“Tomorrow was a draw, but I still have the rights to Niichama for today, don’t I, Neechama?”

“Uh!”

Shiori made a face like Oh, that’s right. No, it isn’t!

“No, listen, Mitsuki. That’s a bit… inappropriate, isn’t it? These days, that’s ‘out,’ right?”

“What are you saying, Niichama? We’ve always bathed together before.”

“No, that was back when you were little.”

“Two years ago you were in 2nd grade. 4th grade is bad news, right? I’ll get banned! I’ll be ‘deleted’ in so many ways!”

“Listen, Niichama. Even Mitsuki will be in the upper grades next year. I doubt I’ll ask to bathe together from next year onward. This might be the last opportunity.”

“Wasn’t 2nd grade already the last opportunity?!”

Mitsuki looked at me with a serious face. Seriously, what is this…?

“You see, Niichama, there is an ‘Ordinance Concerning Public Bathhouse Health Standards,’ and Nagano Prefecture stipulates that males and females aged 10 and older should generally not bathe together.”

This 4th grader is starting to say some very difficult things… What is up with this kid? Was she always like this?

“And Mitsuki is currently 9 years old. Bathing together is recognized by the law!”

“Wh-wh-whaaaaat!!”

Recognized by the law?! Then it won’t be a target for a ban! No, no, no, no, that’s not the point…

Mitsuki sighed, placed both hands on my shoulders, and stared at me from point-blank range.

“Niichama… in other words, Mitsuki is still a child. There couldn’t possibly be anyone in this world who gets excited by a child’s naked body. Unless! …Are you that kind of pervert, Niichama?”

Mitsuki looked at me with a sorrowful expression.

“…Th-there’s no way that’s true!! I’m not a lolicon! Fine!! In that case, there’s no problem!! Mitsuki, let’s get in!!!”

“Yay! Waaaay! Niichama, let’s play with the rubber ducks!”

Pulled by the hand by Mitsuki, I headed toward the bathroom.

Just as I left the room, I glanced back at my sister… I-I can’t even describe it… she had a face that would totally ruin her image.

Eh, is this okay? Am I gonna be deleted? Am I gonna be erased by my sister, or the country, or the site management?