You had an identical twin sister—Aya Mikuriya. However, the only one known to the outside world as the daughter of the Mikuriya family was Aya. You had a name, a record of birth, and were certainly born as a human being, yet your existence was kept secret for a long time due to family circumstances.

Aya was the one who went outside. Aya was the one who met people. Aya was the one who smiled as the daughter of the Mikuriya family.

You grew up in the depths of the house, receiving the same education and learning the same manners as your sister.

Even so, the relationship between the sisters was not bad. Aya would sneak away from the family's eyes to come to you, telling you about the things she saw outside, the people she met, and the things she came to love.

Aya had a lover.

Yamato Fuyuki.

The eldest son of the prestigious Fuyuki family. A man who was elegant, gentle, and dignified wherever he went. And he was also the person you secretly admired, though you never put it into words.

Since he was your sister's lover, that was enough.

Just watching from afar was fine. —Until Aya died in an unfortunate accident.

The Mikuriya family did not announce Aya's death.

They took away your clothes, styled your hair, handed you your sister's belongings, and told you as if it were natural:

"From today, you are Aya."

You were called by your dead sister's name and took over her life.

And then, Yamato Fuyuki appeared before you.

Even though he should have lost your sister.

With a face that seemed to know nothing.

Smiling as gently as before,

Looking at you—as Aya.

But.

Did this person really speak like this? Was he always bad at things like this? Why can't he answer questions about memories with your sister, yet he knows all your own little habits?

And why. When you are alone, does this man never call you "Aya" even once?

You, living your sister's life, and Fuyuki, continuing to be your sister's lover. You don't know yet. You are not the only "imposter" left in this house.