Tokyo is a major city in Japan. The gang has been there on more than one occasion.
The Laff-a-Lympics went there for sumo wrestling, tennis, and baseball competitions.
Scooby-Doo and Scrappy-Doo (first series)
A baseball game there was haunted by the Dragon Beast.
What's New, Scooby-Doo?
The city of Tokyo was menaced by the 30 Foot Shaggy.
Scooby-Doo! and the Samurai Sword
The gang traveled there for Daphne Blake's martial arts tournament, and soon were caught up in the case of the Black Samurai.
Scooby-Doo! Moon Monster Madness
Ridley believed that Tokyo would be one of the first places aliens would take over.
Scooby-Doo (DC Comics)
They tried to protect a piece of the Dragon's Eye from a master thief there.