Image heavy.
Sorry if this isn't allowed.
Here's from Aohige from apforums.
-Unexpected hobby of Zoro: Zoro likes to flip through picture guides of weapons, as well as collected book of bounty heads.
-Sanji's name was Naruto!: Originally Sanji was named Naruto. But Naruto started serialization, so he changed his name to Sanji.
-Various ideas of Nightmare Luffy: There were ideas such as "polite and serious" Luffy with a side-part hair style. Him taking in shadow of a swordsman to use swords was already decided as well.
-Ace's tattoo: Sabo's initial was carved into Ace's tattoo! (duh)
-Luffy was terrible at lying even back when he was a little kid! (duh)
-Dadan was originally a man: Early design of Dadan, he was a male. He wore a kasa hat, shades, and smoked a pipe.
-The pretty lady shown in the pic... is the current Dadan WHEN SHE WAS YOUNG.
-Ace and Garp's conversation had hidden meaning: Without letting the readers know, they were actually talking about Roger! (duh)
-Spooky face on Chopper's head!?: This was originally going to be used in Sky Island, Robin doing a Face Flower on back of Chopper's head. It was way too creepy to be used.
-Chopper's early design was a zebra-raindeer that smokes cigar. Holy hell.
-Chopper will never fall in love with a human. He can befriend them and respect them, but he won't find them attractive as a mate.
-Early Franky: Franky's early designs were slim, tall man who spent much of his life in jail. He could forge weapons, but could not use them.
-FRANKY'S SUPER UNDERWEAR HOLDS HIS CRAFTING "TOOLS" AT ALL TIMES.
-Usopp and Garp's interaction: Although it was cut due to page limitation, there was a scene originally where Garp and Usopp have a conversation!
-Usopp shows his concern about his dad in the Red Hair Pirates, and Garp asks Usopp to take care of his grandson.
-Eye-patch pirate will show up later in the series
-Early designs: cigar-smoking raindeer as doc, Naruto/Sanji as cook, a skeleton as a musician, a sniper as First Mate, a female navigator, and a swordsman warrior.
-Most of these have carried through in the series, but the shipwright was a midget
-and Franky was a skinny weaponsmith.
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