The entire cast consists of genderless gems explicitly kept that way at creator Haruko Ichikawa's direction, with English translations using they/them pronouns as a conscious industry shift from binary defaults. All nine lead voice roles go to female actors, normalizing non-traditional identity presentation as the foundational character design rather than incidental diversity.

Episode arcs show Phos losing limbs, gaining new abilities and forms, and questioning their place, with body modification and outsider status (e.g., Cinnabar's isolation) forming recurring motifs that some analyses link to identity themes. These elements are prominent and deliberate but secondary to the core adventure, encyclopedia quest, battles, and existential/Buddhist-inspired exploration of self and duty; the plot would not collapse without the gender framing.

No race-swapping, explicit social justice lectures, or creator activism statements appear. Reception highlights the pronoun choice and androgynous designs as notable but frames the series primarily as visually striking storytelling with philosophical depth rather than message-driven activism.