One Piece: Ultimate Villain

Get Isekai'd into a world like One Piece is amazing, especially when accompanied by a cheat like system... but why is this system so weird?

[Congratulations Host, you've been chosen as the Ultimate Villain!]

[Please behave like the Ultimate Villain, and get the reward!]
...
“Nami, you wouldn't want Nojiko to fall into my hands, right?”

“Robin, you wouldn't want Luffy to lose his chance to become Pirate King, right?”
...
“Looks like I have to accept my fate as the Ultimate Villain!”