Gay anime characters in demon slayer

Suma is one of the wives of Tengen Uzui. She is also a skilled kunoichi and member of the Demon Slayer Corps. Suma is a young woman with fair skin, black hair with short bangs over her forehead, and round eyes.

While the official English translation has the character using gendered pronouns, it's likely that the characters in the story don't know either way, since they have an androgynous appearance. Overall, the fanbook is the best source for this character's gender being non-binary.