Kasumi Ashihara, daughter of the island temple's Chief Priest Master Komoshi, exists within the secret cult operating there. Engaged to Bungo, she secretly pursues a lesbian affair with Misa, an island servant. Kasumi exhibits a sadistic nature, finding enjoyment in torturing those under her authority, particularly Misa and the girls Junko and Ruka when penalizing their misconduct. Her relationship with Bungo is complex; though their engagement appears superficial, she displays genuine concern for him. This is shown when she somberly informs Ryo and Ruka of his sacrificial death and urges them to escape.

Destined by her father to be one of the cult's sacrifices, Kasumi's involvement in the rituals connects to the island's red flowers. Their scent induces passionate ecstasy, influencing her actions. Despite her manipulative and cruel tendencies, she demonstrates moments of loyalty, especially towards Bungo. Her fate culminates in the third episode when her father, Master Komoshi, sacrifices her. He uses her as an offering to sustain the cult's god, Master Mizuno, her blood visibly staining Komoshi's hands afterward.

Her background remains partially obscured, but her role as the priest's daughter places her within the island's power structure. She navigates conflicting loyalties—to her father's cult, her fiancé Bungo, and her lover Misa—ultimately becoming a victim of the traditions she helped perpetuate.