Pocket Monsters Blue first appeared in Japan as a CoroCoro Comic mail-order edition on October 15, 1996.
The Japanese Blue version followed the February 1996 launch of Pocket Monsters Red and Green. It was initially a special edition available by mail order to CoroCoro Comic subscribers, rather than a normal general retail release.
Blue included updated in-game artwork and revised dialogue. Its code, script, and artwork later served as the basis for the international Pokémon Red and Blue releases, although those versions preserved the different Pokémon distributions associated with the Japanese Red and Green pair.
The date is often confused with Blue’s later retail availability. The Japanese version eventually reached general retail on October 10, 1999. Pokémon Yellow, another enhanced first-generation release, arrived in Japan on September 12, 1998, and was designed with stronger connections to the anime.