Content Warning: This section of the guide includes discussion of illness, death, sexual harassment, and child abuse.

Lilia is the protagonist and primary narrator, alongside Devryck Bramwell. She is 20 years old and from a working-class background. Her mother died from a mysterious parasite four years ago, and she struggles to pay for medical school with the aim of discovering what happened. Her life changes when she writes a “theoretical” paper on the parasite, which is real and researched privately by a wealthy university on Dracadia island. Her professor recommends that she go there, where she is a granted a semester to study on a scholarship.

There, she is placed in an advanced class with the parasitology professor, Devryck. He’s about a decade older than her and comes across as incredibly surly, condescending, and harsh—but very intelligent. Lilia is attracted to him and seeks to know more about the parasites that he studies, Noctisoma. Through the events of the novel, she develops both a romantic relationship and a working relationship with him: They fall in love, and she is brought on to assist in his research. Before the climax of the novel, their attraction to one another has many risks, particularly for Lilia.