Fujiwara no Yukinari is a supporting character who serves as a mentor and a steadfast friend to the young protagonist, Abe no Masahiro. His connection to the main character stems from a past favor; the legendary onmyouji Abe no Seimei once helped Yukinari, and in gratitude, Yukinari pledged to act as Masahiro's guardian during his coming of age ceremony.

Yukinari demonstrates a warm and encouraging personality. From his very first meeting with Masahiro, he takes a genuine liking to the boy and pushes him to reach his full potential. He shows a deep understanding of the social challenges Masahiro faces, particularly the jealousy and resentment the young onmyouji receives from others simply because he is Seimei's grandson. This awareness makes Yukinari not just a teacher, but also a perceptive ally who recognizes the burden Masahiro carries.

In the story, Yukinari's role is primarily that of a supportive mentor. He is notably aware of Masahiro's secret activities fighting dangerous youkai, suggesting a level of trust and insight into the boy's life beyond official duties. His own skills as an onmyouji are put to the test during the Kazane Arc, where he falls victim to a curse. A vengeful spirit named Hozumi no Moronao mistakenly targets Yukinari, confusing him for his own grandfather. Fortunately, Masahiro is able to step in and successfully exorcise the spirit, saving his mentor. This event highlights the reciprocal nature of their relationship, where the student is able to protect the teacher, directly contributing to Yukinari's story development by placing him in a vulnerable position that deepens his bond with Masahiro.