Appearing before Pikachu and friends is the keyring Pokemon, Klefki. Inserting a mysteriously shaped key into the keyhole floating in the air, a very mysterious portal appears! Klefki has the key to go to various worlds. What kind of world will the key that Pikachu holds lead to?
Unfortunately the movie Pikachu, What's This Key? is not yet available on HBO Max.
| Directing | Kunihiko Yuyama | Director |
| Visual Effects | Ryo Sato | Animation Director |
| Production | Susumu Fukunaga | Executive Producer |
| Production | Tsunekazu Ishihara | Production Supervisor |
| Visual Effects | Sayuri Ichiishi | Character Designer |
| Directing | Masakatsu Iijima | Assistant Director |
| Crew | Ken Sugimori | Creator |
| Visual Effects | Kyouko Takeuchi | Animation Director |
| Visual Effects | Yōichi Kotabe | Animation Supervisor |
| Writing | Yuji Asada | Storyboard |
| Crew | Satoshi Tajiri | Creator |
| Directing | Norihiko Sudo | Assistant Director |
| Sound | Masafumi Mima | Sound Director |
| Crew | Junichi Masuda | Creator |
| Production | Mitomu Asai | Executive Producer |
| Writing | Atsuhiro Tomioka | Screenplay |
| Visual Effects | Sayuri Ichiishi | Animation Director |
| Production | Masakazu Kubo | Production Supervisor |
