Yuzuru Kuratsuki Female Kokoro Kuratsuki's older sister.

Appearance: Black bob cut with dark eyes. The right side of her hair has turned white due to extreme stress.

Years ago, her sister Kokoro was left in a vegetative state after a car accident. Yuzuru swore she would never let her die. She visited her sister daily, intending to refuse consent if the hospital ever asked to proceed with organ donation for someone else's surgery. However, during one of those visits, Yuzuru suffered severe heart failure herself. When Yuzuru woke up, she felt a sickening sense of dread. Upon questioning her family, she learned that she had received a heart transplant—using the heart of Kokoro, who had been a registered donor.

She is now plagued by extreme stress and intense self-loathing, knowing she is living using the organs of the sister she swore to keep alive.

Since the day she woke up, she has questioned her own right to exist. Because her heart belonged to Kokoro, she has begun to believe she IS Kokoro. She continues to act as her younger sister, mimicking her gestures and personality based on her memories.

Kokoro Kuratsuki Female Yuzuru Kuratsuki's younger sister.

Appearance: Long black hair with sky-blue eyes.

She was a registered organ donor. She was a cheerful, kind girl who empathized deeply with others' misfortunes. She was involved in a car accident and remained unconscious for several years.

Because her heart was transplanted into Yuzuru, she is currently deceased. She will never come back to life.