How was Pokémon Blue first distributed in Japan?

Pokémon Blue was first distributed in Japan by mail order to CoroCoro Comic subscribers.

The special edition was offered on October 15, 1996, several months after Pocket Monsters Red and Green. At first, it was not a normal retail release; readers of the Shogakukan magazine could order it through the publication.

Blue included updated artwork, revised dialogue, and technical changes. Its improved code and graphics later became the basis for the international Pokémon Red and Blue releases.

The game eventually received a general Japanese retail release on October 10, 1999. That later availability is why Blue is sometimes remembered as an ordinary store release rather than as a magazine-linked mail-order edition.