Moe Mizukoshi is a student at Kazami Academy, one year senior to the protagonist Junichi Asakura. She is the older sister of Mako Mizukoshi. Her family runs the Mizukoshi Hospital on Hatsune-Jima. Moe is known for her gentle and polite demeanor, but she can be dim-witted at times and has a tendency to fall asleep suddenly in any situation, even while walking. This narcoleptic trait is linked to the lingering magic of the island’s once-everblooming cherry trees, which grants her the ability to see the spirit of a deceased childhood friend in her dreams. She often carries a small xylophone simply because she likes the sound, though she does not care to become a skilled player. A member of the school’s music club, she is a capable pianist. She is also an honor student with a fondness for fortune-telling, and she has a subtle mischievous side that occasionally surfaces.

Moe’s greatest passion is cooking nabe, a type of Japanese hot pot. She frequently spends lunch breaks on the school rooftop preparing and eating nabe with her younger sister Mako, and she can talk at length about its ingredients and preparation methods. Her warmth and patience are most apparent in her relationship with Mako, whose competitive and headstrong nature contrasts with Moe’s calmness. Aside from her role as a caring sister, she works as an occasional helper at the family hospital. In D.C.S.S.: Da Capo Second Season, Moe appears as a supporting character who continues to interact with Junichi and the other students, offering gentle guidance and a comforting presence. Her motivations are simple: she enjoys the small routines of daily life, looks out for her sister, and maintains her connection to the supernatural elements of the island through her unique dreams. Over the course of the story, her unchanging kindness and reliability remain consistent, reinforcing her role as a serene and beloved upperclassman.