I'm asking what pronouns Foo Fighters uses for herself, or what other characters use when referring to him/her in the Japanese version of JoJo's Bizarre Adventure Part 6: Stone Ocean. I am aware that he/she's actually something like a colony of plankton living inside a woman's corpse, and that the English version elected to use "they/them", but I want to know what pronouns are used in the Japanese version.
They're called "F・F" which is (obviously) abbreviation of Foo Fighters, or sometimes called as "あんた" which is colloquial version of "あなた", which means "you".
As far as I remember, they weren't called with pronouns, though Japanese fanbase sometimes call them as "she/her", though it's quite rare since we also usually call them as Foo Fighters or F・F.
Side note: In Japanese, there's no words that's equivalent to "they/them", so we usually call non-binary people as their name or nickname. So, in this case, "F・F" is the equivalent word of they/them. That might be the reason that English version used "they/them" as Foo Fighter's pronouns.