What was the Japanese title of the first Pokémon video game pair?

The Japanese title of the first Pokémon video game pair was Pocket Monsters Red and Green.

Game Freak released Pocket Monsters Red and Green for the Game Boy in Japan on February 27, 1996. The games established the original Kanto region, the first 151 Pokémon, and the series' central loop of catching, training, battling, and trading.

An enhanced Blue version followed in Japan. For international markets, Nintendo and Game Freak used Pokémon Red and Blue instead; the original Japanese Green version was not released overseas in its original form.

This naming difference creates a frequent mix-up. Red and Green are the Japanese originals, while Red and Blue are the familiar Western pair. The two versions were designed to encourage trading because certain Pokémon appeared in only one version.