Crystal and Yu are a couple that everyone admires. Crystal is a pure and refined beauty, and Yu is a handsome and elegant guy. They like to go to the dilapidated ancient rooftops in the suburbs to watch the stars.
Crystal has been having the same dream since she was a child. In the dream, there was a vague person holding a purple crystal and gave it to her, but she couldn't see the person in the dream clearly.
Until the night of her 20th birthday, everything changed————