The episode begins with the arrival of Yayoi, Keitaro, and Eiko at the old F-Tunnel in O-City, Tokyo. Yayoi and Keitaro decide to focus on exploring the old tunnel, based on Keitaro's intuition. They prepare themselves with various protective items, including a doll that escaped from a previous battle.

As they enter the tunnel, Eiko loses contact with Yayoi and Keitaro. She meets Anna Misaki, a YouTuber who investigates haunted places. Anna tells a terrifying story about a ghost in the tunnel that traps and torments people. As they walk, they find themselves in a loop that leads them back to the tunnel entrance. Additionally, they notice strange large sacks appearing in the tunnel, further intensifying the eerie atmosphere.

Meanwhile, Yayoi and Keitaro realize that Eiko is in danger. They suspect she is in another tunnel, the Old Old F Tunnel, which is even more unstable. They establish the basic rules for their rescue mission, emphasizing that Eiko's safety is the top priority and that they must not use powerful spirits that could cause the tunnel to collapse.

As they attempt to enter the old F-Tunnel, Yayoi and Keitaro are taunted by an evil spirit wearing the face of another ghost they have encountered before. Despite the risk, they are determined to go in and rescue Eiko.

At the end of the episode, Yayoi and Keitaro enter the Old Old F Tunnel, resolved to confront the evil spirit waiting for them in order to save Eiko.