May is the ship's doctor aboard the Cha-Cha Maru, the vessel captained by Tita Mu Koshigaya in the course of the story. She is a young woman of twenty-six years who serves as the medical officer and also possesses extensive knowledge in physics and theology. Her background includes early training in Chinese martial arts, making her a capable fighter who can overpower opponents much larger than herself. Before joining the crew, she was said to prioritize research over human life, but her perspective shifted after meeting Tita, with whom she developed a close bond akin to that of sisters. Within the crew's family-like dynamic, May acts as a maternal figure, providing emotional support and practical advice. She is the person Tita turns to as a confidante. Her motivations center on protecting the crew and ensuring their well-being, especially Tita's. May's notable abilities include her medical expertise, her scholarly knowledge in multiple fields, and her combat proficiency, which she uses to defend the ship and its passengers. Over the course of the narrative, her character shows a softening of her earlier detached intellectualism, becoming more invested in the lives and safety of those around her. She plays a key supporting role, contributing both through her healing skills and her physical strength in moments of danger.