Shouko Yuhara worked as a secretary at Arimiya Tower alongside Tatsuya Katori. She harbored a personal vendetta against Kamoshige Arimiya for his treatment of her mother, one of his discarded lovers. Kamoshige's abandonment caused her mother severe depression due to her genuine feelings. Shouko expressed satisfaction at Kamoshige's death but prioritized claiming his inheritance.

She allied with Katori, who sought revenge for his own family. Together, they pursued the PIN to Kamoshige's safe containing hidden wealth. To extract information, Shouko participated in interrogating and sexually assaulting his stepdaughters—Misora, Chisato, and Shion Arimiya—though none knew the PIN. Katori discovered the code through visions from Kamoshige's spirit.

Upon opening the safe, Shouko was stunned by the fortune inside. Katori betrayed her after inheriting the wealth and becoming Arimiya family head, forcing her into sexual servitude. In one instance, she was restrained alongside Emiri Kasai with a vibrator inserted in both.

Shouko engaged in sexual acts with Katori, initially driven by self-arousal. Her sexuality appeared fluid, including an instance of molesting Shion Arimiya. Her name combines "auspicious, happiness, blessedness" (祥) and "child" (子) for "Shouko," while "Yuhara" means "hot water/bath" (湯) and "field/plain" (原). Both her mother and Katori's mother were former lovers of Kamoshige.