The story centers on a triad of protagonists connected by metaphysical and biological bonds. While the film explores deep emotional intimacy, it lacks explicit depictions of non-heteronormative identities or queer romantic arcs.

Ruka serves as the narrative's primary investigator and emotional anchor. She actively navigates supernatural mysteries, disrupting traditional male-led adventure tropes by providing the central agency for the story.

The setting and character designs reflect a contemporary Japanese coastal context. The film uses the unique biological origins of Umi and Sora to challenge human identity boundaries through a metaphysical lens.

The narrative prioritizes a naturalist worldview and the sublime mysteries of the ocean. It de-emphasizes human-centric social structures like organized religion in favor of cosmic interconnectedness.

No explicit physical or neurodivergent disabilities are central to the plot. However, the characters' biological divergence from humanity provides a narrative space for those existing on the periphery of standard experience.