The Pokémon Tower was originally constructed to house the souls of deceased Pokémon. However, sometime before the events of the thirteenth chapter, Lavender Town townspeople began to see sightings of ghosts in the tower, leading the majority of them to become distrustful of their neighbors and of outsiders. It's after Red hears that Green disappeared while investigating the tower, that he too decides to investigate. Inside, he finds the tower enshrouded by a thick fog and infested with zombie Pokémon, which are being controlled by the fog. Figuring out that the fog is actually Gastly, Red defeats the Pokémon and frees Green from its control. It's soon revealed that Team Rocket, led by Koga had been using the tower as a secret base of operations. The two manage to defeat Koga, and, though damaged by the battle, the tower is freed from its corrupted state.