Ren Nanase is a 22-year-old nurse at St. Juliana Hospital, known for her bright, friendly demeanor and devotion to patient care, earning her an "angel in white" reputation through sincere professionalism. She has long aubergine hair, often in a ponytail, and green eyes.

Prior to St. Juliana, she attended nursing school where rumors implicated a faculty member as a rapist. Her direct confrontation led to her becoming his sex slave, subjected to intense degradation.

At St. Juliana, Dr. Ryuji Hirasaka, a physician with severe personality disorders, uncovers her secret romance with inpatient boxer Naoya Ohkawa and her match-fixing schemes to advance his career. Hirasaka blackmails her into submission. Enduring sexual exploitation and psychological torment, she develops Stockholm syndrome, forming an emotional bond with Hirasaka that deepens into genuine love. This compels her to recruit new victims for the hospital's exploitative network.

Her degradation includes forced defecation during medical tests observed by staff and sexual acts witnessed by her hospitalized mother. She later becomes pregnant. In one narrative conclusion, she murders Hirasaka after he awakens, confessing her love during arrest. An alternate ending sees her marry Hirasaka, relocate to the countryside as a "good wife," and perpetuate his experiments.