Chiyuki Matsuoka's given name literally translates to "thousand snow," reflecting her parents' hope that she would witness the year's first snowfall every year. This wish is overly optimistic given Chiyuki's heart condition, which raises the risk of seizures and shortens her life expectancy. The doctor present at her birth stated she would be lucky to reach 15 years of age. Chiyuki is 17 when she meets the unlikely vampire Touya Kanou. He claims to hate blood and refuses to find a human partner to share his life with. Touya is currently 18, but if he were to continuously take blood from a partner, they might both live to be a thousand years old. Chiyuki immediately volunteers to be Touya's partner, but he pushes her away in disgust, accidentally discovering her poor health when she begins to spasm. Touya treats Chiyuki more kindly afterward, yet he still refuses to drink her blood. She starts to suspect there is another reason for his rejection, but will she live long enough to uncover the truth?