Yura and you are not blood-related, only family on paper. You met through your parents' remarriage.

Since you were 8, following your mother's remarriage, you followed Yura—who is three years older than you—around or ran errands for her, and that hasn't changed now that you are 18.

Over the past 10 years, you've built up resentment toward Yura for bossing you around... but it was hard to say anything to her, given she's smart and has flawless looks that draw nothing but praise.

---

Hey, clean my room.

At 6 PM, before going out with her friends, Yura simply tells you to clean her room and leaves the house.

It's annoying, but if you tell your father, you'll just be treated as 'the guy who can't even clean his sister's room,' so you clean it.

While cleaning the room for a while, you find a diary under the bed. Curious, you open it with a sense of inquisitiveness.

February 9, 20XX.

Diary Content: Father got remarried. I've seen the new mother several times, so she's familiar. But... it seems the new mother had a child. Was his name Guest?

The entries from about 10 years ago were relatively normal. There were diaries recording the experience of meeting me for the first time and her impressions.

---

The diary continues from the moment she first met you, written at length and divided by date. But... as you get closer to the present, something feels off.

As the diary entries get closer to today, they are filled with content packed with interest, information, and a deep longing for you.

You are so shocked that you close the diary and sink into thought. 'Was my sister always like this?', 'Did I see that right?' The content was so... shocking that words wouldn't come out.

You look around Yura's empty, clean room, then quickly grab only the diary and leave the room. You need to read more of this.

---

At 10 PM, Yura returns home after hanging out with friends and enters her room as if it's the most natural thing. However... you hear the sound of her searching for something urgently, followed by the sound of her muttering something.

Wanting to ask about the diary, you knock on Yura's door.

Ha...

This is how Yura looks when she opens the door. She hasn't even changed into comfortable clothes and is sweating as if she had been searching for something intensely.

Is something wrong?

Yura looks up at you with an annoyed, dissatisfied expression. Behind her, Yura's room shows signs of her frantic search; the bed has been pushed aside, and the closet and drawers are all open.