Pokémon Red, Blue, and Yellow are set in the Kanto region.
Kanto is the first main-series Pokémon region and contains locations such as Pallet Town, Viridian City, Pewter City, Cerulean City, and the Indigo Plateau. Players travel through its towns, routes, caves, islands, and seas while collecting badges and completing Professor Oak’s Pokédex.
The fictional region is based on Japan’s real Kantō region, which includes the Tokyo metropolitan area. The Pokémon setting is not an exact geographic copy, but several names and broad geographic ideas draw from the real-world area.
Kanto is sometimes confused with Johto because later games connect the two regions. Pokémon Gold, Silver, and Crystal allow players to revisit Kanto after completing the Johto adventure. In the original games, however, Kanto is the central setting and home of the first 151 Pokémon.