Fifteen-year-old Miaka Yuki, focused on passing entrance exams for Jonan Academy to join her best friend Yui Hongo, grapples with a strained relationship with her mother stemming from her parents' divorce. This fuels her persistent need for maternal approval and contributes to her people-pleasing nature. Academically average, she compensates with determination. Her defining traits include optimism, outgoingness, naivety, and sentimentality. She demonstrates compassion, generosity, and a strong capacity for forgiveness, perceiving herself as considerate. However, she exhibits recklessness, poor common sense, and a tendency toward self-sacrifice, frequently requiring rescue despite occasional displays of courage or insight. Her gluttony is a notable weakness, often leading to obsessive focus on food, and she is recognized as an exceptionally poor cook. She also engages in anime-inspired daydreaming.

Transported into the Universe of the Four Gods book alongside Yui, Miaka becomes separated from her friend and is designated the Priestess of Suzaku. Her initial motivation is selfish—to use Suzaku's three wishes for personal goals like academic success and physical attractiveness. After falling in love with the Celestial Warrior Tamahome, her goals shift toward finding a way to be with him. Gathering the seven Celestial Warriors of Suzaku—Tamahome, Hotohori, Nuriko, Chichiri, Tasuki, Mitsukake, and Chiriko—forms her central quest. Her role requires her to remain a virgin to maintain her priestess powers. Miaka proves capable of appealing to others' compassion, gradually winning over initially hostile warriors like Nuriko, Tasuki, and Mitsukake. Despite frequently being placed in peril, including multiple attempted rapes aimed at nullifying her powers, she demonstrates moments of agency, such as injuring herself to escape a pocket dimension or using unconventional attacks like a hip check or German suplex against assailants. Her decisions often drive the plot, sometimes negatively, as seen when her actions lead to Tamahome's brainwashing and endanger other warriors during the kodoku arc. Over time, her wish priorities evolve from selfishness to selflessness, culminating in her final act as priestess where she prioritizes restoring the world and saving Yui over personal happiness with Tamahome.

Following the main events, Miaka marries Taka Sukunami, the reincarnation of Tamahome. In the Eikoden OVA, she becomes pregnant at age eighteen. During this pregnancy, she enters a coma, allowing Mayo Sakaki to temporarily assume her role as Priestess of Suzaku within the book world. Subconsciously, Miaka had transferred her unborn child, Hikari, to Mayo, intending for the child's strong connection to Taka/Tamahome to stabilize the deteriorating Universe of the Four Gods. Miaka later awakens from the coma and resumes her life as a wife and mother.