[3] The two-part film stars Kotono Mitsuishi as the voice of Sailor Moon and Chibi-Chibi alongside Kenji Nojima, Misato Fukuen, Hisako Kanemoto, Rina Satō, Ami Koshimizu, Shizuka Itō, Junko Minagawa, Sayaka Ohara, Ai Maeda, Yukiyo Fujii, Nana Mizuki, Marina Inoue, Saori Hayami, Ayane Sakura, and Megumi Hayashibara.
At the airport, Mamoru gives Usagi a ring, but before he can propose is suddenly killed by the mysterious Sailor Galaxia, who steals his Golden Crystal and disappears.
Meeting Seiya, she learns that the Starlights are searching for their princess, who fled to Earth when Galaxia attacked their planet.
In the 30th century, Chibiusa notices time distortions affecting the future, but is told to remain by Neo Queen Serenity.
In her palace, Galaxia reflects on seeking a star worthy of her power and discovering Chaos, an immense embodiment of evil at the center of the galaxy.
Concerned that Sailors Uranus, Neptune, Pluto, and Saturn, who have gone to their respective home bases, may be in danger, she asks for Kakyuu and the Starlights' assistance.
Sailor Moon, Kakyuu, the Starlights, and Chibi-Chibi travel to the Outer Guardians' respective home bases, but learn that they have already been killed.
Lethe kills Luna, Artemis, and Diana, blaming the Silver Moon Crystal for causing conflict as she and Mnemosyne reluctantly joined Galaxia after she destroyed their planets.
In doing so, she hopes Sailor Moon's powers will overload from grief and destroy Chaos, which lurks in the Cauldron, thereby leaving her as the sole ruler of the galaxy.
Chaos merges with the Cauldron and injures Galaxia, planning to take the Silver Moon Crystal and rule the galaxy.
Some time in the future, Mamoru and Usagi marry, pledging their fidelity to each other, their friends, and their mission to guard the Earth.
[12] In April 2022, it was announced that the sequel covering the Stars arc of the manga was to be produced as a two-part anime film project, titled Pretty Guardian Sailor Moon Cosmos The Movie (劇場版「美少女戦士セーラームーンCosmos」, Gekijōban Bishōjo Senshi Sērā Mūn Kosumosu).
[13] Majority of key staff members from Eternal two-part film returned, with Kazuyuki Fudeyasu writing the screenplay, Kazuko Tadano designing the characters, and original creator and mangaka Naoko Takeuchi chief supervising the films' production, while Tomoya Takahashi had taken over Chiaki Kon's position as a director.
[16][17][18] The main voice cast from Sailor Moon Crystal and Eternal reprised their respective roles, and had already recorded their lines for the first film prior to the announcement.
[19] Kotono Mitsuishi, the voice of Usagi Tsukino/Sailor Moon, confirmed that Cosmos will mark her final performance as the titular character.
[4][22] That same month, it was announced that Megumi Hayashibara and Nana Mizuki were cast as Sailor Galaxia and Princess Kakyuu respectively, while Kotono Mitsuishi would reprise her role as Chibi-Chibi.
[10] In June 2023, it was revealed that Japanese actress Keiko Kitagawa, who previously portrayed Rei Hino/Sailor Mars in the 2003 live-action series, was cast as Sailor Cosmos.
[15] The theme song for the two-part film is titled "Moon Flower" (月の花, Tsuki no Hana), sung by Daoko.
[31] In June 2024, it was announced that Netflix acquired the streaming rights for the two-part film, and it was released worldwide on August 22, 2024.