What was the original Japanese title of the Pokémon games released internationally as Red and Blue?

The games released internationally as Pokémon Red and Blue were originally titled Pocket Monsters Red and Green in Japan.

Pocket Monsters Red and Green launched for the Game Boy on February 27, 1996. Japan later received a revised Blue version, which included updated artwork and other changes. The international Red and Blue releases were based largely on this enhanced Japanese version rather than directly reproducing the first Red and Green builds.

The Japanese Green edition was not released outside Japan. This explains why many international players know the first pair as Red and Blue, while Japanese release histories describe the franchise’s beginning as Red and Green.

The paired versions used different Pokémon availability to encourage trading. Players needed both versions, or connections with other players, to complete the original 151-species Pokédex. The naming difference is therefore a release-history fact, not a separate generation.