The Pokémon region based primarily on Japan’s Kantō region is Kanto.
Kanto is the setting of the first-generation games Pokémon Red, Green, Blue, and Yellow. It contains familiar locations such as Pallet Town, Viridian City, Pewter City, Cerulean City, and Saffron City. Its geography and names were inspired by the real Kantō region of Japan, which includes Tokyo and surrounding prefectures.
The region is also the main setting for the first Pokémon anime journey. Ash begins in Pallet Town, travels through Kanto’s cities and routes, challenges eight Gym Leaders, and eventually competes in the Indigo Plateau Pokémon League.
Kanto is sometimes confused with Johto because the two regions appear together in Pokémon Gold, Silver, and Crystal. Johto is based on Japan’s Kansai region and lies west of Kanto in the game world. Later regions followed other Japanese areas, while some were inspired by places outside Japan.