Yuki Tamura studies under Professor Ramujo, an antiquarian at Jonan University. Her entanglement in the central conflict sparks when she meets Ryou Matsumoto, a screenplay writer, for lunch following a bar introduction. At the restaurant, they find an envelope addressed to Ramujo, which Yuki offers to deliver. Unbeknownst to her, the envelope holds a forged authentication letter for the stolen artwork "Flames of Sekijou," linking her professor to an antique forgery ring run by criminal broker Goda. After delivering it, Yuki agrees to Ramujo’s request to temporarily safeguard the envelope, unaware of its contents.

This act marks her as a target for Goda’s organization. Following a brief departure from town, Yuki reunites with Ryou for prolonged personal interaction. Upon returning, Goda’s henchmen ambush them at her apartment, resulting in their capture. During a confrontation at Goda’s waterfront hideout, Yuki seizes an opportunity to flee amid a diversion orchestrated by Ryou. She drives recklessly to alert Detective Mochizuki about their predicament and Goda’s location.

A narrative framing device later reveals Yuki is actually Ryou’s real-life girlfriend working at a movie studio. The entire escapade—including her role as Ramujo’s student and involvement in the forgery scheme—unfolds as part of Ryou’s rejected screenplay.