Rain god Zaza’s real form
I lowkey think Oda’s gonna change the Rain god’s appearance later on if he does decide to fully reveal who it is, main so because when Killingham generated the Giant kids their nightmares it also included “Nika” based on the kids depictions of him from “stories” they “heard” Nika was different than who they thought of him to be, similarly when Killingham created Zaza he says “stories heard” so it means even he doesn’t know Zaza’s real form, meaning we could end up seeing a new character affiliated with/to the Rain god looking wayyy different than Killinghams interpretation.
Edit: (Not likely but) Looking back at the panel when Zaza is introduced, to me it looks like Zaza is made of glass or some transparent object thats holding water inside her, so Zaza might just be a person with a devil fruit that allows them to transform into glass or into something similar that can hold water and dispose of it as they wish giving others the illusion of “rain”. Since devil fruit users are weak against sea water it would seem kind of broken to give a water based powers so that also leads me to believe this might be a twist that Oda could use.
Plus given the fact that if Zaza is made of water it would’ve gotten its ass fish man karate’d so i doubt Oda would leave that plot hole in there