Episode 9 resumes the narrative thread from its thrilling climax, with Mi-jeong immersed in watching the videos Dong-jin had meticulously curated for her. The footage includes poignant glimpses of her childhood home and a poignant apology video from a former friend, who confesses to spreading malicious rumors about her. Concurrently, the spotlight shifts to Jung-hyeok, who is hot on the trail of the stalker who had injured the recent victim, amidst Dong-jin's journey to meet Mi-jeong.
Upon capturing the suspect, Jung-hyeok's rage overflows, culminating in a physically violent confrontation, which leads to his subsequent transfer. Days later, Eun-sil pays Jung-hyeok a visit, bearing the ominous news of Dong-jin's disappearance. Realizing he hasn't had contact with Dong-jin in some time, Jung-hyeok embarks on an investigation into his whereabouts.
During his search of Dong-jin's room, Jung-hyeok uncovers subtle hints—Mi-jeong's name highlighted in books she had translated—that suggest a deeper connection. He convenes with Eun-sil to delve deeper into Dong-jin's recent demeanor. They venture to Dong-jin's house, where Eun-sil unveils the circumstances behind Dong-jin's living arrangements in the modest room, clarifying that Dong-jin had indeed been stalking Mi-jeong. They also uncover a mysterious glow-in-the-dark message, "Shine on you," inscribed on the windowsill, which serves as a cryptic clue guiding Jung-hyeok to Dong-jin's personal blog. Using Dong-jin's student ID, found written on an old report about Mi-jeong, as the password, Jung-hyeok gains access to the blog, revealing Dong-jin's intricate records, theories, and exhaustive data on Mi-jeong.
While spending the night there, Jung-hyeok peruses through Dong-jin's blog as Eun-sil drifts into slumber. In the dead of night, an alarm blares on Dong-jin's concealed phone beneath his desk. Driven by curiosity, Jung-hyeok trails Mi-jeong, who takes a solitary stroll at 2:30 AM, informing her that he believes she is a witch—perhaps more so than anyone else suspects.
Meanwhile, Eun-sil awakens to discover a damning report Dong-jin had compiled about Jung-hyeok. The report notes Jung-hyeok's unprecedented disregard for rules concerning Mi-jeong, yet his inexplicable immunity to harm. By breaking these rules unscathed, Jung-hyeok inadvertently validates Dong-jin's hypothesis, leading to the stunning realization that Jung-hyeok himself is Mi-jeong's male counterpart—a "witch" in his own right. The episode concludes with an intense moment, as Eun-sil spots Dong-jin across the street, the two figures standing a mere 10 meters apart, teetering on the edge of an unknown fate.
