The only concrete evidence we have to determine Neferpitou's gender appears in the official databook "Hunter × Hunter Character and Word Data Book." In it, Neferpitou is referred to using the pronoun "彼” (kare) which is usually translated to “he.”[22][23]
When speaking, Neferpitou uses the pronoun “boku,” (translated to “I” in English) which is used by boys and young men, but it's also used by some less femenine sounding women.
Neferpitou's different depictions in both the anime and the manga.
Neferpitou is shown naked with a flat chest.[24] Later in the manga, Neferpitou is described like a "mother" protecting a child.[25]
In the cover of Volume 28 which is implied to be based off the coronation of Virgin Mary, Neferpitou takes the middle position which corresponds to Virgin Mary's.
From all this, it should be assumed that Neferpitou does not have a specific or “confirmed” gender. Because of this, this article uses non-gendered pronouns such as "they/they're."
In the manga, Neferpitou's chest is totally flat. In contrast, the 2011 anime may depict Neferpitou by giving it a prominent bust.
So, it is possible that Neferpitou's gender in the manga differs from the anime.