A girl who moves into the Kanemasa mansion atop the hill with her family. She has a rare genetic disorder known as SLE, which leads her to stay inside her home during the day and only come out at night. She and her family are fans of the essays and novels written by Seishin Muroi, and is the reason they moved to Sotoba. Sunako dislikes people calling her name with the honorific “chan.”
Sunako was originally a beloved daughter of a well-off family. She was bitten by a vampire Western noble, who was a guest of her family, and died. When she revived as a Shiki, her family kept her confined and sent her servants to feed on. After some time, she finally left her refuge and went on a journey to find her family, who had moved. However, her journey went on to no avail for so long that by the time Sunako realized it, her entire family was all dead.
She later bites Muroi Seishin. When Tatsumi informs her of Chizuru’s death and the villagers’ plot to eradicate the Shiki, she orders him to start an all-out war.