Kei Yuzuki is a principal character who appears in the second episode of the Vampire Princess Miyu original video animation series. He comes from a wealthy family that holds great expectations for him, and he is described as a handsome young man who attracts the attention of many girls at his school.

Kei is portrayed as a student whose academic performance has recently begun to decline. This downturn appears connected to the pressure he feels from his family, particularly from his often-absent mother and his brother, both of whom push him to improve his grades. His personal life is marked by a deep-seated fear of aging and death, a vulnerability that ultimately defines his path in the story.

In the episode titled A Banquet of Marionettes, Kei's life changes upon meeting a shinma named Ranka. He seems to instinctively sense Ranka's supernatural power and, driven by his fear of mortality, pleads with her to prevent him from growing old and dying. Their relationship deepens when he later professes his love for Ranka, and she finds herself developing genuine feelings for him in return.

The narrative role of Kei Yuzuki is central to the events of this single OVA episode, where he becomes the focus of competing interests between the vampire princess Miyu and the shinma Ranka. The story culminates when Kei makes a conscious choice to embrace Ranka and her offer of an escape from his human frailty. As a result of their bond, Kei is transformed into a living puppet, and both he and Ranka are ultimately banished into the darkness.

Information regarding his development beyond this episode or any notable supernatural abilities of his own is not documented. His significance is tied directly to his interaction with Ranka and the resolution of the episode's central conflict.