The stalker initiates contact by sending Saki an anonymous email containing illicit photographs of her changing clothes and masturbating, accompanied by the message "I know your everything". This establishes a pattern of surveillance and intrusion into her private life. Using the photographs as leverage, the stalker issues progressively demanding and immoral orders via email. Despite Saki's initial resistance, his persistent manipulation fosters her psychological dependence on compliance. He demonstrates meticulous prior observation through detailed knowledge of her daily routines and vulnerabilities.

Later, the stalker escalates by confessing romantic feelings while reinforcing control through blackmail. He deliberately sabotages Saki's relationship with Shuji by sending him photographic evidence of her coerced sexual activities. His possessiveness surfaces through expressed jealousy when Saki spends time with Shuji, demanding immediate compensatory acts like public masturbation during their date as "payment". Operating exclusively through anonymous digital channels, he maintains psychological control without physical presence. The character functions solely as an external catalyst for conflict via persistent blackmail and psychological manipulation.