The Pokémon region based on Japan’s Kansai region is Johto.
Johto was introduced in Pokémon Gold and Silver and their later enhanced version, Pokémon Crystal. It is located west of Kanto, the setting of the original Pokémon games, and the two regions can be visited within the same game world.
The geography and culture of Johto draw heavily on Japan’s Kansai area, including locations associated with Kyoto, Osaka, and nearby regions. Cities such as Ecruteak City reflect traditional Japanese architecture and cultural imagery, while the region's historical atmosphere distinguishes it from the more metropolitan Kanto setting.
A common mix-up is confusing Johto with Kanto because both regions appear together in Generation II games. Kanto is based on the real-world Kanto region around Tokyo, while Johto is the neighboring western region inspired primarily by Kansai. Hoenn, Sinnoh, and later regions draw from different parts of Japan or other countries.