The upcoming anime film We Are Aliens (Ware Ware wa Uchūjin) has revealed additional cast members as it heads toward its September 25 Japan premiere.

Gaku Sano joins as Seiya Toda, a friend of the protagonist Tsubasa, with Reika Ōzeki voicing the character as a child. Arisa Sasaki plays Elmo Matsushita, Toda's friend, and Edo Harumi voices a calligraphy teacher.

The film follows Tsubasa and Gyōtarō, two boys who were inseparable as elementary students before jealousy and misunderstandings fractured their friendship. Years later, when memories of their past resurface, they must reckon with what drove them apart. The main cast includes Ryōta Bandō and Amane Okayama as adult versions of the characters, with child actors Yūto Maki and Tasuku Nakagome—selected through auditions—voicing them in flashback scenes.

Director Kōhei Kadowaki handled scripting, storyboarding, and editing for the project. He previously created the ending sequence for BEASTARS season two and directed music videos for YOASOBI. Yaffle, known for producing tracks for Fujii Kaze and Kenshi Yonezu, composed the score. The theme song "Sasakure" (Split) comes from the artist adieu.

We Are Aliens is produced by NOTHING NEW and marks a collaboration with French animation studio Miyu Productions, which joined in June 2025. The film already has festival pedigree: it screened at the Cannes Film Festival's Directors' Fortnight in May and competed at the Annecy International Animation Film Festival in June.

Beyond Japan, the film will screen at several international venues including the Ottawa International Film Festival (September 23–27), Melbourne International Film Festival (August 6–23), and New Zealand International Film Festival (July 29–August 9). CHARADES is handling international distribution, with deals already secured for Taiwan, Singapore, Hong Kong, and Thailand.