What was the first Pokémon theatrical film released in Japan?

Pokémon: The First Movie was the first Pokémon theatrical film released in Japan.

The Japanese film premiered on July 18, 1998, under the title Pocket Monsters the Movie: Mewtwo Strikes Back. It was directed by Kunihiko Yuyama and centers on Mewtwo, a genetically engineered Pokémon who challenges ideas about identity, creation, and purpose.

The international English release used the title Pokémon: The First Movie and reached North America in November 1999. It became a major box-office success despite receiving mixed critical reviews, especially regarding changes made to the English adaptation.

The film is often remembered together with the short Pikachu’s Vacation, which accompanied many theatrical screenings. That short is a separate story, while the main feature is the Mewtwo-centered film that began the Pokémon anime movie series.