Adaptation
Toei announced the film in June 2024, with the voice cast from Fuuto PI's anime adaptation reprising their roles.[2] Due to the popularity of the anime adaptation, initial plans for the theatrical version involved continuing its story, but scheduling constraints at Studio Kai prevented an immediate continuation. After discussion between director Yōsuke Kabashima and Studio Kai's production manager, Daisuke Furuya, they decided to adapt the first manga volume into a film or original video animation, as a full series was considered difficult. As such, the screenplay was written specifically for a theatrical anime.[3] The production team had initially considered adapting either the fourth manga volume—which featured the Puzzle Dopant, a character absent from the web anime—or seventh volume, which introduced Kamen Rider Accel. However, the production team decided that featuring Kamen Rider Skull was the most critical element for attracting audience interest, leading to the selection of the sixth volume for adaptation.[4]
Kabashima studied Kamen Rider W: Begins Night to prepare for the production. However, he cut certain aspects he disliked of Kamen Rider W 's treatment of Skull's story.[5] A new character named Oshima Nagi was created for the movie as an antagonist. The director tried to avoid portraying Oshima as a pitiful character, and instead tell an interesting story about him and Saeko.[6]
Development
Kabashima praised the performance of the two main actors, stating that they needed minimal guidance. He commended Tsuda's performance as Narumi for his easy-going portrayal and faithfulness to the original live-action television series. Kabashima intended to depict Narumi as a role model for Shotaro and others to look up to. His scene with Philip was written as a reference to the catchphrase "Count your sins" from the original series, although Narumi says the line more calmly.[5]
Shotaro cries in three scenes, which Kabashima felt were crucial to put effort into animating for the sake of appealing emotionally to the audience. In particular, the final scene where Shotaro falls asleep next to Tokime was intended to be deeply moving. He spoke to the animator, Ebinama, and asked him to create a unique visual effect of a film of tears for these scenes. Since it was the first time that the scenes from the original manga were being voiced, Kabashima wanted them to be especially well-done.[7]
Kabashima named Masami Obari as a major directorial influence for his animation choices. He combined 3D animation with 2D animation in several scenes, such as the first time Shotaro enters Narumi's office.[5] While he was pleased with the final result, he felt there was room for improvement in animation quality and direction; in particular, he wanted the animation team to be able to improve and rework scenes on their own.
Voice casting
Ayumu Murase, who voiced a young Shotaro, expressed his enjoyment of the dynamic with Kenjiro Tsuda's character, Sokichi Narumi.[8] Similarly, Kabashima named Tsuda's portrayal of Narumi as one of the best parts of the work. Kabashima had been impressed by Kikkawa's portrayal of Narumi in Kamen Rider W: Begins Night, and hoped that Tsuda would also play the character well, particularly what he described as Narumi's cool aspects.[7] Yoshimasa Hosoya and Kōki Uchiyama, who voiced Shotaro Hidari and Philip respectively, welcomed the announcement of the theatrical anime adaptation. Hosoya found his part relatively straightforward, as the source material was a live-action drama with lines largely consisting of explanatory dialogue and monologues. He described young Shotaro as a "classic anime protagonist" and expressed that tone with an over-the-top delivery style, particularly in comparison to the stoic Philip. Reflecting on his previous performances as Shotaro, he noted that his character's image had already been firmly established when he was first cast in the role.[9]
The antagonist Oshima was voiced by Jun Fukuyama. Kabashima emphasized Oshima's ear piercings, gifts from Saeko, as a reflection of his humanity.[6]
Music
The film features the theme song "Niau Otoko ni Nare" (似合う男になれ), written and composed by Kōji Kikkawa and performed as his character Sokichi Narumi, who he played in the original Kamen Rider W series.[10] Kikkawa sought to convey Narumi's perspective when singing the song. As part of this process, he read the script, formed a mental image, and then created lyrics that fit the story. The song's lyrics were intended as a message of encouragement to the young people featured in the film.[8]
For the fight with the Ocean Dopant, the studio initially intended to use the theme song "W-G-X (W Goes Next)" from the web anime, but changed it to "W-B-X (W-Boiled Extreme)" by Aya Kamiki and TAKUYA, the theme song from the original series, to better suit Shotaro and Philip's first battle.[11] The song "Nobody's Perfect" was added by Kabashima to fit well with scenes he looked forward to, as well as future episodes of the TV series.[6] The soundtrack was released on November 9, 2024, featuring thirty-three tracks composed by Kōtarō Nakagawa and Shuhei Naruse
