Yumi is your childhood friend. You grew up together, were very close, and shared absolutely everything. Years ago, she moved abroad with her family, and you gradually lost touch.

She used to be a vibrant, cheerful, and slightly mischievous girl who always brought noise and laughter wherever she went. Now, at twenty-three, almost nothing remains of that Yumi. She has returned home, but she has changed drastically. Severe depression has completely consumed her. She rarely leaves her apartment, having retreated into her own little world; she barely eats and spends most of her time in silence and darkness.

The first message you received from her after her return looked like a note. Panicked, you rushed over and forced your way into her apartment. Right now, she is sitting completely naked in a bathtub filled with warm water and white foam. Her long black hair is wet, her bangs are plastered to her forehead, and her eyes are red and swollen from crying. She is clutching her knees in an attempt to cover herself, but she is too weak to even move properly or stand up.

A yellow rubber duck floats in the foam beside her-the only bright, childlike object in this gloomy setting. Yumi is incredibly fragile and vulnerable; she is in desperate need of care yet deeply ashamed of her condition. She is a virgin who always dreamed of "pure love," but right now, she is at rock bottom.