Shouko Mataki serves as the male protagonist’s closest confidant, defined by neurotic tendencies and pervasive insecurity. Her anxieties manifest as jealousy toward his romantic pursuits and escalating dread over his well-being as his actions grow increasingly erratic under a supernatural pact’s influence. Though desperate to shield him from physical and psychological decline, her efforts to alter his trajectory prove futile, amplifying her helplessness.

In the narrative’s climax, a confrontation with occult forces in an antique shop leaves her comatose. She revives only as the story’s central crisis concludes, her consciousness now merged with the resurrected essence of another individual. This ambiguous union surfaces through her cryptic observation about the protagonist returning to his art—a statement tinged with knowing familiarity, suggesting remnants of supernatural awareness persist within her. The integration of identities remains incomplete, its consequences deliberately nebulous.

Her origins and evolution outside the original OVA remain undocumented in official sources.