The Straw Hats visits an island, known as Mecha Island, where a fisherman sings an old folk song about a Golden Crown. Searching for that mysterious treasure, they find a hidden entrance into the island. The island's leader, Ratchet, impressed with the find and in search of the Golden Crown himself, invites the crew to join him in his search and the crew along with Ratchet and his henchmen enter the cave. As it turns out, the islands true form, is that of a giant turtle. Ratchet, who had known this all along, uses his mechanical castle to take control of the turtle, in order to use it, to take over the world. Now the Straw Hats have to stop not only Ratchet, but also the helpless turtle, from crashing into a nearby island.
Unfortunately the movie One Piece: Giant Mecha Soldier of Karakuri Castle is not yet available on HBO Max.
| Directing | Konosuke Uda | Director |
| Visual Effects | Koichi Morishima | Key Animation |
| Visual Effects | Nobuyuki Iwai | Key Animation |
| Visual Effects | Yukiko Kobayashi | Key Animation |
| Visual Effects | Satomi Kani | Key Animation |
| Visual Effects | Ani Kato | Key Animation |
| Visual Effects | Kozue Horanai | Key Animation |
| Visual Effects | Yukie Akiya | Key Animation |
| Visual Effects | Eisuke Matsubara | Key Animation |
| Visual Effects | Haruki Miura | Key Animation |
| Visual Effects | Takayuki Manaka | Key Animation |
| Visual Effects | Shin'ichirou Fukushima | Key Animation |
| Visual Effects | Yuji Hakamata | Key Animation |
| Visual Effects | Kumi Nakajou | Key Animation |
| Visual Effects | Kazuhiro Muto | Key Animation |
| Visual Effects | Takao Kôzai | Key Animation |
| Visual Effects | Lee Si-eun | Key Animation |
| Visual Effects | Kim Bo-young | Key Animation |
| Visual Effects | Kim Yong-sik | Key Animation |
| Visual Effects | Yang Byung-gil | Key Animation |
| Visual Effects | Seo Jung-ha | Key Animation |
| Visual Effects | Masao Takeda | Key Animation |
| Visual Effects | Yoshinobu Aohachi | Key Animation |
| Visual Effects | Jouji Ooshima | Key Animation |
| Visual Effects | Motoaki Satou | Key Animation |
| Visual Effects | Chisato Kawaguchi | Key Animation |
| Visual Effects | Shino Ikeda | Key Animation |
| Visual Effects | Michiko Notsu | Key Animation |
| Visual Effects | Shigeki Sato | Key Animation |
| Visual Effects | Nishiki Itaoka | Key Animation |
| Visual Effects | Shizuo Kawai | Key Animation |
| Visual Effects | Kazuya Hisada | Key Animation |
| Visual Effects | Masayuki Takagi | Key Animation |
| Visual Effects | Yumiko Tomiki | Key Animation |
| Visual Effects | Kazue Kinoshita | Key Animation |
| Visual Effects | Masahiro Okamura | Key Animation |
| Visual Effects | Kazuya Saito | Key Animation |
| Visual Effects | Shigenori Taniguchi | Key Animation |
| Visual Effects | Kazuyuki Ikai | Key Animation |
| Visual Effects | Miho Hirayama | Key Animation |
| Visual Effects | Yumenosuke Tokuda | Key Animation |
| Visual Effects | Shuichi Ito | Key Animation |
| Visual Effects | Nobuhiro Masuda | Key Animation |
| Visual Effects | Katsumi Ishizuka | Key Animation |
| Visual Effects | Hitoshi Inaba | Key Animation |
| Visual Effects | Takayuki Gorai | Key Animation |
| Visual Effects | Satoru Iriyoshi | Key Animation |
| Visual Effects | Yoshitaka Yashima | Key Animation |
| Visual Effects | Kenji Yokoyama | Key Animation |
| Visual Effects | Yoshiko Shimizu | Key Animation |
| Visual Effects | Eisaku Inoue | Animation Director |
| Visual Effects | Eisaku Inoue | Character Designer |
| Writing | Masahiro Ito | Screenplay |
| Writing | Eiichiro Oda | Comic Book |
| Art | Ryuji Yoshiike | Art Direction |
| Editing | Masahiro Goto | Editor |
| Crew | Motoi Takahashi | Cinematography |
| Crew | Hirosato Ônishi | Cinematography |
| Sound | Yasunori Iwasaki | Music |
| Sound | Kohei Tanaka | Music |
