The film does not feature identifiable LGBTQ+ characters or themes. The narrative focuses on a young boy's friendship with a mermaid and the challenges they face in a fishing town, exploring themes of music, community, and environmentalism without incorporating LGBTQ+ elements.

The film does not feature any identifiable transgender characters or themes. Its narrative centers on a young boy's relationship with a mermaid and the community's reaction to her presence, without exploring gender identity beyond cisgender roles. The story contains no elements that depict or allude to transsexual experiences.

The film features Lu, a mermaid with unique abilities related to water and sound. Her actions and resolutions to conflicts rely on these supernatural powers, not on direct physical combat, martial arts, or melee weapon fights against male opponents.

Lu Over the Wall is an original animated film. All characters are new creations for this production, meaning no prior established character genders exist for a gender swap to occur.

Lu Over the Wall is an original animated film. It does not feature characters adapted from prior source material or historical figures with established racial identities. Consequently, no race swap occurs.