What was the original Japanese title of Pokémon Red and Blue?

The original Japanese games corresponding to Pokémon Red and Blue were titled Pocket Monsters Red and Green.

They were released for the Game Boy in Japan on February 27, 1996. The pair introduced the first 151 Pokémon and established the version-exclusive structure that encouraged players to trade with one another.

International players often assume the first pair was Red and Blue because those are the familiar English titles. Japan did receive a Pokémon Blue version later, first as a special edition and subsequently as a retail release. The code, artwork, and presentation of Japanese Blue formed the basis for the overseas Red and Blue games, while the distribution of Pokémon followed the Japanese Red and Green structure.

This history also explains why references to Pokémon Green appear in anniversary discussions. Green was not released internationally as the original counterpart to Red; overseas audiences instead received Blue. The distinction is about regional release naming, not a different franchise or generation.