Which Pokémon game version was released first in Japan: Red or Green?

Pokémon Red and Green were released simultaneously in Japan.

The two original versions launched together on February 27, 1996, for the Game Boy. Their version-exclusive Pokémon encouraged players to exchange creatures, making interaction between separate cartridges part of the core experience rather than an optional extra.

Japan later received Pokémon Blue as an updated special edition. For international markets, Nintendo and Game Freak used the Blue version's improved code and artwork while retaining the distribution differences associated with Red and Green; those releases were titled Red and Blue.

Because overseas players generally know the franchise through Red and Blue, some assume Red was the original Japanese counterpart to Blue. In fact, the first Japanese pair was Red and Green, while Blue was the later enhanced Japanese edition.