The more you remember about Shitji, the more cringe WCI becomes with all the "you're the kindest" bs
The problem is not Sanji. Whole cake is indeed an amazing arc. The problem is Oda's sexism that he is projecting toward Sanji (or Brook). Oda simply do not see those behavior as very problematic and when he does he plays them like a joke.
This is the big problem of One Piece.
For us, metoo passed by. So we understand how problematic those behaviors are. But not Oda. He is trapped in a format and a still very sexist culture.
Remove the sexism of Sanji or the sexist jokes, and Sanji will be an amazing and indeed, very kind character.
That's why I choose to ignore Sanji's moment of sexism (while remembering that they still exists), it allows me to really appreciate the arc for what it is supposed to be.
I would love for Oda to come back on his work and erase some of those very problematic moments.
This one however is really not a good example of said sexism.
Sanji is not asking Nami to buy a sex slave. Anyone with two neurons can understand that it would be dumb. He is just asking Nami if they can save this girl too (since they intend to buy Caimie back) to bring her back with them.
Its simple simpness, nothing more.
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Also, I want to add that this is not something we can't do nothing about. We can try to make Oda understand why it is problematic.
Send him letters, makes reasonnables critics on twitter etc.
The purpose is not to trash the manga but raise his awareness of the subject and maybe make Sanji grow a little bit.
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Also (x2)
Respect Sex workers please.