Produced by Bakken Record and distributed by Toei Company, the film is directed by Jun Matsumoto from a script written by Riko Sakaguchi and stars Hio Miyazawa, Ai Hashimoto, Aju Makita, Mutsumi Tamura, Kenji Hamada, Mie Sonozaki, Tomomichi Nishimura, Fumi Hirano, Miki Mizuno, Kimiko Yo, and Tokuma Nishioka.

The film follows high-school student Koyomi Takasaki meeting Kazune Takigawa, who reveals to him that he is her boyfriend in the 85th parallel world.

He encounters young Shiori who then runs away and finds himself at Imaginary Science Research Institute where his father works.

Arriving at his mother's house, Koyomi realizes that he is in a different world where he has chosen to live with his father, his grandfather is alive, and Yuno has passed away.

Now a high school student, Koyomi is approached by his classmate Kazune Takigawa, who introduces herself as his girlfriend in the 85th parallel world.

An anime film adaptation of one of the two science fiction romance novels by Yomoji Otono, Boku ga Aishita Subete no Kimi e, was confirmed in September 2021.

[13][a] In May 2022, Jun Matsumoto was revealed to be directing the film at Bakken Record, with Riko Sakaguchi writing the script and Shimano conceiving the character designs.

[15] In June 2022, Hio Miyazawa, in his voice acting debut, and Ai Hashimoto were revealed as the main characters Koyomi Takasaki and Kazune Takigawa, respectively; Miyazawa was also set to voice Koyomi Hidaka alongside Aju Makita as Shiori Satō in the film's companion piece To Me, the One Who Loved You.

[4] Mutsumi Tamura, Kenji Hamada, Mie Sonozaki, Tomomichi Nishimura, Fumi Hirano, Miki Mizuno, Kimiko Yo, and Tokuma Nishioka were announced as part of the cast in August 2022.

[10] That month, other staff working on the film were also announced, including Kenzō Ishiguro for planning and production, Yukari Tachibana and Tomoyuki Saito as the producers, Keiichi Kondō, Rika Sasaki, and Kano Komiyama as the character designers, Kenji Fujisaki, Yumiko Ōmae, and Kenji Shibata as the animation directors, Yukari Yasuda as the art director, Yohei Konishi as the cinematographer, and Masaki Sakamoto as the film editor.

Additionally, Suda was announced to be performing the theme song "Kumo wo Kō" (雲を恋う, lit.

[10] The title was based on the old idiom "Rōchō Kumo wo Kō" (籠鳥雲を恋う), meaning "a bird in a basket pining for the clouds in the sky",[19] with Suda explaining that it reflected how Koyomi "yearns for freedom from a state of captivity".

[26] That month, the film was included in the benefits of premium users of au Smart Pass [ja], where they could watch a work at theaters for ¥1,100.

[15] Otono commented that the filmgoers could choose which of the two films would they watch first, stating that "the order in which they are seen will greatly affect the way you feel about them.