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Only I Know that My Sister has a Brother Complex

Chapter 1.1

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Edited by



Chapter 1 ♥ ️ My sister’s summer is too late

Translated by Devxtt

Edited by Silverylazes, Travistann

#[TN update- ‘Onii-chan Notebook’ to ‘Onii-chan Note’]

It was summer that I realized that my high school life was almost half-finished.

I heard the news from a senior in the club.

“Hey, Yusuke. It seems that your sister refused Yamamoto’s confession.”

“Yamamoto….. Oh, that. “

The first person who comes to mind when I hear Yamamoto. He is a third-year senpai, Taichi Yamamoto.

He is one of the most popular people in school. No, the most popular among girls. He is handsome, smart, and good at sports. He has a bright future and aims to join a National University, which is also a bonus. He is the target of admiration for girls, and that can’t be compared with me.

I don’t know him that well personally. But I think he’s a really popular guy when I hear such news, even if I don’t want to.

If an event called “Most Desired Boy to Date” is held in this school, it is arguably Yamamoto-senpai, who will end up being the winner.

He is the kind of guy who would be representative of our school.

It would be no exaggeration to say that my sister, Akari, is also the most popular school girl.

Even though she is only a first-year student, I am impressed by the fact that she has already established her school reputation. And that she has something to watch out for.

And the matter of Akari and Yamamoto Senpai. Everyone thinks that they are one of the best couples to look at.

As an older brother, if a perfect man like Yamamoto-senpai wants to date my sister, then there would be no reason for me to reject the fact that they would date eventually.

…… But Akari rejected his confessions.

According to my seniors, she refused because there is someone else she likes.

“Who is he?”

All of them seem to be in doubt, but the truth is hidden deep within the darkness as that person has nothing more to say.


“What’s wrong? About the sigh.”

“No, nothing…”

In reality, that person is me!

There is no way I can say that.

Who else could blame me for sighing?

“I’m home.”

After all the club activities, I returned home past 7 PM.

When I returned after traveling by train, three family members except me were preparing dinner.

“Oh, you’re back. It was early Today.”

My mother says while arranging the dishes. I don’t like the fact that it sounds like I’m an overtime office worker. Cut that out already.

“I’m home. I’ve finished all my club activities. So I think I’ll be coming home at around this time for a while.”

“That’s great. Then, from now on we’ll eat dinner together.”

……I take it back. I was unconscious. Apparently, my remark was a little off the chart.

“Akari, help me carry your brother’s dishes.”

“Un, I understand.”

Akari responded with a single phrase. As usual, she won’t say more words than necessary.

Akari has always been a cool girl since she was a kid. She’s a little different from the so-called normal high school girl. She’s not so friendly and doesn’t like to spend time with her friends.

But that’s one of the many reasons why my sister is so popular.

Despite the fact that people look at her like she is some kind of cool object of admiration for both men and women to look like a form of “cool beauty.” 

Though she is only in the first year, she is already named the most beautiful girl in the school. It’s good.

Well, from my point of view. When I first heard these, I wondered, “What is cool beauty?”

But when I saw her at the school, I can’t help but understand it’s meaning.


After a long time, our whole family gathers at the dining table. The laughter heard from the TV feels like BGM(*background music), and every person was eating without having a conversation. In the first place, my parents are not the type to start a conversation, so this became the basics for our table manners.

And, after a while…

Suddenly I felt someone intensely looking at me.

However, When I looked at Akari, she was silently picking up a side dish, and there was no eye contact between us.

Well, maybe it was my imagination.

“July 2nd, Thursday.”

Onii-chan came home earlier than usual.

From what I heard, it seems that the club’s work was completed.

To be honest, I would like you to quit the club and come home as early as possible. But … Onii-chan enjoys club activities, so I have no choice but to endure.

But, I’m still lonely. I wish I could stay with him a little longer….. I think.

By the way, Onii-chan came home early, so we were able to eat together.

Today, I learned cooking from my mom. The meat and potatoes I served for dinner were the side dishes I made…… Did you notice Onii-chan?

During the meal, I felt that Onii-chan was looking at me, and maybe he noticed it …!

“Hyaa!…… I love you, Onii-chan♥️”

Yes! It wasn’t my fault!

Akari was conscious of this with all her might, and it seems that she noticed that I looked at her. Yet she intentionally ignored me!

It was such a daunting joke to say ‘Cool Beauty.’

“A girl of dignified beauty? What’s dignified?”

“Even so, Akari, Today you were confessed by Yamamoto-senpai. Right?”

“What happened with being confessed by the most popular boy in the school? You only care for Onii-chan chewing meat and potatoes?”

“Well, ‘Haaah!’ this line…..”

At this time, Akari is taking a bath, and it’ll last for less than an hour. To be exact, it was about 15 minutes. In the meantime, it is customary for me to sneak into Akari’s room and read the “Onii-chan Note” updated by Akari each day.

That’s because, for the past two years, there was not even a single day when Akari didn’t write notes.

The timing of writing the notes varies from day by day. Sometimes it’s before taking a bath, and sometimes it’s written before going to bed or after taking a bath.

For this reason, there are days when you can read it. And days when you don’t…… Today is the former.

I wonder if she was happy to have a meal with me. After dinner, I hurried back to the room and finally found out. But now, I feel very complicated.


“Yusuke, let’s go to the club.”

Next day. 

After the homeroom, someone told me to get ready.

“Yoshiki? I’ll be there soon, wait for me.”

This is Yoshiki Sakurai. My classmate, clubmate, and friend with a well-defined face and brown hair.

“Sorry for the wait.”

“Oh, you’re finally here. Let’s go.”

We left the classroom and walked to the club room on the 4th floor in the next building. It’s been a year and a half since I joined the club, and it’s an important daily routine.

“By the way, have you heard the news yet?”

“Ah … about Akari? I heard from my senior yesterday.”

“No, I’m surprised by the fact that Yamamoto Senpai confessed, but even more I’m surprised to see that there are some people who can refuse Yamamoto’s confession.”

Well, it’s Akari-Chan……and, he adds that while showing a surprised expression. However, his speech was rather light.

That must be the case. And after that, he said;

“Well, it doesn’t matter because you’re a hated big brother.”

Yoshiki makes fun of me and starts laughing.

Yes, he knows we’re on bad terms, so he just wants to mess around with me.

He’s always like this.

“Oh, I agree. Your right!”

Our flow of conversations ends here.

“Thank you for your hard work “

When I opened the door of the club room, I saw a girl sitting on the chair. As soon as she saw us coming, she shifts her gaze from her notebook and looks at us.

“Oh, both of you have finally arrived.”

“… It’s only you Nanami?”

“That’s right, our seniors have supplementary lessons …. By the way, did you hear that? About Akari-chan.”

Nanami grinned.

“That story…….. Akari is like a celebrity.”

“Well, she’s so cute. That’s why nobody wants to neglect this topic.”

Nanami House, my childhood friend, smiled and muttered. I’ve known her since she was a child. We are in the same second year of high school, in the same class, and the same club.

Her house is in the neighborhood, and our parents are on good terms. That is the reason why we are good friends.

We are of the same age. We have been together since childhood. It doesn’t change whether we become elementary or junior high students… Finally, we took the same high school exam.

I think that childhood friends of the opposite sex are naturally separated during puberty.

In our case, it’s different, we also have the same club, and we will go to the same college in the future. I sometimes think that our workplace will also be the same until employment.

……Well, the reason is that in all of those times, Nanami invited me to join whether it’s this high school or the club.

“Oh, by the way, Yusuke, do you have plans when the club activities are over today?”

“Today? I have no plans.”

“Well, then…. Would you like to go out for dinner, together? It’s going to be late since the club activities are over … See, tomorrow is a holiday, right?”

Dinner? Maybe it’s okay once in a while.

“Okay, let’s go.”

“Really? I’m glad!”

As soon as I agree, she smiles.

What is the dish you wanted to eat so much…?

“If so, then let’s invite Yoshiki as well? After the club activities are over, I think Yoshiki can join us.”

It must be a good dinner, and I think it’s better to have many people.

I made a suggestion with that in mind. But when Nanami heard that, she frowns.

“Hmm … I had that thought that Yusuke would say that …”

She muttered.

Eh, did I say something strange?

After the club activities, Nanami looks sullen, and Yoshiki, who also has a complicated expression, squeezes pasta for two hours. Finally, I returned home past ten o’clock.

It’s funny, where did I make the wrong choice….?

“Hmm … I’m tired today.”

I finished the bath and went inside my room, I grumbled.

Even though I was sitting at the shop all the time, it felt mentally exhausting probably because I was concerned about Nanami, who was in a bad mood.

Then I spent a lot of time without doing anything and picked up my smartphone for no particular reason.

Yes, there was nothing else I had wanted to do.

Internet surfing is just one of Akari’s hobbies that she can do in her room.

It’s been two years since I started reading Akari’s notebook.

As I read the notebooks written every day, I learned that a surveillance camera was set up in this room, and a microphone was installed recently. Akari, who has nothing to do with school life, occasionally talks about me. I learned a lot by observing from a distance.

But I haven’t done anything to this day.

Rather, I don’t even know what to do, but it might be the correct answer.

I’m sure if I tell our parents, they will do something about it. I can’t predict what will happen in the end, but I’ll be able to stay away from Akari for the time being. I shouldn’t have to keep up with it.

But I just can’t do that.

If I do that, I’m sure everyone will have a hard time.

Mom, dad, and Akari.

I’m scared, after all. I am afraid that a few words would destroy my everyday life.

No, I’m not a bad person, and I don’t care, but … I wonder why, after all, that courage doesn’t come out.

I have no choice but to endure.

Let’s be patient until one day Akari changes her mind and realizes the mistake of what she is doing. That was my conclusion.

For that reason, there is a limit to what I can do in this room because of the surveillance camera.

I’m also an adolescent boy. I want to see one or two of those erotic videos.

However, if you think that Akari actively monitors all the activities, I do in this room…Yes, it’s awful.

I can’t do that.

“Are you awake, Akari?”

I was hovering over my smartphone when I heard my mother’s voice from behind the door.

She’s not here for me but Akari.

While listening to the conversation through the door, it seems that she came for Akari to ask for a bath.

Time is… Eleven o’clock? Yeah, at this time, I guess she had already written the note.

Following my mother’s footsteps, the door of the next room closes, and I can hear the sound of footsteps going downstairs. I’ll wait a little bit just in case.

Well, let’s go and check Today’s notes.

Smiling at my dexterity, I touched the drawer as usual.

…… Then I noticed that there was an unfamiliar notebook placed inside.


One word is written on the cover.

The only notebook I always read is “Onii-chan Note.” I don’t remember seeing this one.

“Plan……? Perhaps…….”

I didn’t recognize this notebook, but it caught my attention.

As I read Akari’s “Onii-Chan Note,” I remembered that sometimes it says “for plan” or “plan is going well.”

At that time, I was ignoring it. I thought it’s about something stupid, but perhaps this notebook contains detailed information about the “PLAN.”

“Un, well, let’s read this……”

I picked up the notebook and placed it on the desk, and opened it.

It was the familiar handwriting.


A strong heart is essential for the success of this Plan.

If you feel like you’re about to fail, read this note and remember the perfect future you think of.

“All right, you can do it.”

What is this? A message to your future self?

It is interesting, but I don’t have the time to read it further. I turned to the next page.


Lock up Onii-chan.

【Why is it necessary?】

Lock up Onii-chan so that he can’t live without me.”

…… Akari said something absurd!

What should I do?

1) Ignore it.

2) Ignore it.

3) Ignore it… As if I could!

“What’s this! You’re locking me up….huh? Haha, that’s a nice joke!”

My consciousness is fading, but I have to continue reading until the end.

No … I want to run away …


I love my Onii-chan.

I’m sure it will be eternal and will never change until death.

I want to marry Onii-chan, bear his children, and want to stay close to him until death.

…… But we are blood-related siblings. This fact cannot be overturned.

And it also means that my desires will not be fulfilled.

“Even if I confess to Onii-chan, I’m sure he will reject me. We can’t be in a relationship.”

I know that Akari likes me, but it feels strange to put it into words.

Or rather, it had felt very heavy.

“-So I decided to confine my Onii-chan.”


I was surprised because I leaped too much.


1) Onii-chan starts living alone.

2) Nextyear, I will also be living separately.

3) Then, I’ll lock him up.

Ehhh… That’s absurd…

【What is Needed for the Plan?】

The trust of Onii-chan and the people around you is essential for this Plan.

Trust. In other words, trusting the fact that I hate Onii-chan.

To lock up Onii-chan, it means that the whereabouts of Onii-chan will be unknown. I don’t know how long it will take to finish everything. In the meantime, building trust is very important because it’ll keep me away from suspicion when my mom, dad, or Onii-chan’s friends try to find his whereabouts.

You wouldn’t think that the sister, who hated him so much, would have been hiding her brother.

Next, I have to deceive Onii-chan.

“I’m sure he doesn’t know that I love him so much. And when he’s off guard, the first step of my plan will succeed.”

Anyway, I think the second half is probably impossible.

Because I know everything…

“Then I’ll confine him and spend some time together.”

But, I have to improve my cooking skills so I can feed him.

Then…. I’ll take a bath with Onii-chan. We will watch a movie or drama and sleep together.

“And finally with Onii-chan…… Unn, perfect.”

Perfect? No, please don’t give me that.

“And if Onii-chan can’t live without me … this plan is complete.”

To do so, I have to stay away from Onii-chan until graduation.

It’s tough. I really want to talk to him and go to school together. I want us to date on holidays, and if we’re lucky we can sleep together…..

But I’m patient.

That’s the only way I can be with Onii-chan.

“Because we――”

“Because we are brother and sister.”

Why do you stubbornly try to keep a distance between us when you say that you love me that much. I finally found the answer to this question.

“I see…… So this was the Plan.”

In the first place, I haven’t said a word about living alone after graduation, but there are a lot of things I want to do.

After all, this kind of Plan is like a child’s fantasy. Even if it succeeds, it seems unlikely that it will continue to work.

…… But if I look at such a plan, should I ignore her like the time before I had read this.

No, I can’t do it.

If left as it is, then it will be irreversible.

“I have to do something about it …”

Just before the summer vacation of the second year of high school.

I made up my mind.

” I have to stop my sister’s plan.”

The time limit is one and a half years until high school graduation.


Read only at Travis Translations


Read only at Travis Translations


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