When a character in the image seems to be a futanari, but it's not 100% certain. Signs of futanari include intercourse with a stomach bulge and cum, condom wrappers or penetrative sex positions with thrusting and sex noises. Whether the character is canonically a futanari or not, whether related pictures have a penis showing or not, and whether the artist clarifies that it is futanari or not aren't relevant. So long as it cannot be confirmed visually, this tag can be used.