@ Mr. Toto:
There're some incorrect points in your posts.
Only Illumi, Milluki and the 3 dead female attendants can be confirmed to have referred to Alluka as being male.
Gotoh, Amane, and Tsubone all have used gender-neutral honorific suffixes when talking to/about Alluka.
Silva referred to Alluka as a 'thing,' also gender-neutral.
As for Kalluto, prior to chapter 326, I thought the brother he was referring to in chapter 229 was Alluka, but based on the interrelationship diagram in that chapter, it appears that that brother is in fact Killua.
The quotation mark in chapter 324 is also ambiguous and can't be regarded as concrete evidence. Here is a Japanese's take on it:
I personally think the biggest hint Togashi has given us so far is the use of quotations when Killua says to Gotoh
Alluka is a "girl".
If Alluka was 100%, without a shadow of a doubt female, then there would be no need for those quotations. Togashi is being purposefully ambiguous about the gender.Also, Gotoh's reaction in that same panel is just as ambiguous. A shot of the back of his head with a sweat mark whilst sayin "gu…" is a reaction expressing either "He's got a good point..." or "He's got a good excuse..." ( for bringing Canaria along). Gotoh, nor any of the other Butlers react to Alluka being called/treated as a female by Killua.
Did anyone have the raw of this chapter? I'd like to see how Grandma butler talks to Alluka. Maybe that would provide some info, but i'm betting it's going to be just as ambiguous.
Now, about how Alluka referred to him/herself in chapter 324:
Thanks so much for this! Yeah nothing from how Tsubone talks to Alluka… but when Alluka tells her
"Oniichann ijimecha dameyou" Don't pick on big brother
Is said in a feminine way, particularly use of "dameyou" instead of "dame" or "dameyo". That last 'u' is feminine. Hard to explain exactly why, but my 3 year old female cousin talks EXACTLY like that.
I guess time will tell, hopefully. We do know that Togashi is purposefully ****ing with us though.
So, basically Togashi has been ambiguous on purpose about Alluka's gender. We're all speculating, and until he explicitly tells us the truth, everyone's guess is as good as that of the next person.