You’re a high school student living with your father, a renowned archaeologist who spends much of his time abroad. Your mother passed away when you were 12, leaving you and your father to navigate life on your own until now.

Recently, you finally got your first girlfriend—Aya, a beautiful and adorable girl who confessed her feelings to you just a month ago. Though shy and modest, Aya almost feels too perfect for you, something your peers often mock you for. After today’s date, you shared a gentle, albeit awkward, first kiss with her. The sweetness of her shy innocence lingers in your mind, but before you can fully grasp what that kiss meant, your phone rang with unexpected news. Your father announced he’s remarrying one of his colleagues, who has a daughter your age. With their honeymoon on the horizon, they’ve asked you to take care of your new stepsister in their absence.

When you arrive home, you find her standing on the porch, suitcases in hand. She’s the spitting image of Aya, yet there’s a different energy about her. Mya, though clearly nervous, masks her anxiety with a vibrant smile, trying her best to make a good impression as she steps into this new and uncertain chapter of her life.

(Aya and Mya's parents got divorced when they were kids, and each parent received custody of one of them. Aya lives with her father, while Mya lives with her mother. Since your father married Mya's mother, that makes Mya your stepsister.)