No System + wish fulfillment + character growth + original Devil Fruits + original plot, no joining an existing crew + collecting beauties + kills without hesitation, neither a saint nor a babysitter + multiple worlds (middle and later stages)
Luffy, I accidentally killed your grandpa. You won't hold it against me, will you?
Luffy, some tattooed guy with a long face named Dragon called you unfit to be his son. As your "good buddy," I couldn't stand it, so I took him out for you. No need to thank me, buddy!
Luffy: ...
Momonosuke, your mom's gone... Oh, your dad's gone too.
Momonosuke, I took care of your sister for you, and I also killed that disgrace of a grandfather of yours. How are you going to thank me?
Ace, your dad... Oh, Roger's dead now.
Ace: ...
"Sorry, I forgot you're Whitebeard's devoted son!"
"What? Doflamingo, your mom's dead too? But what does that have to do with me?"
Imu: Why are there so many maids on your ship?
"You don't get it. I may not want them, but I won't give them away."
Many years later, a crew member asked, "Captain Luo Chen, why do you blow up Little Ogre Island every time we reach a Blue Star?"
Luo Chen: Because I love the island so much, it makes me explode with joy!
Explosions are the most beautiful fireworks. If the island doesn't sink, I'm no man!
There's a bond between him and the female crew members, that's fine. The key is that you're targeting Garp's family; otherwise, we're friends. I hope Luffy's family suffers even more. The current One Piece has strayed from its original vision; it's just a bunch of second-generation adventurers, fighting villains but not caring about their fate—it disgusts this longtime fan.
I'm not giving this five-star rating to brag, though. While I'll be writing hundreds of thousands of words in the One Piece world, this book is a multiverse story; once One Piece ends, I'll be adding other worlds. Readers can post the worlds they'd like to see in the comments, and I'll see if I can write them. If I can, I'll observe the timelines and create an outline while I'm writing One Piece. It has to be Japanese manga; Chinese manga won't do.
It's worth noting that some of the female characters in the original work have been altered quite well, such as the courtesan Hiyori and the young Ba Jin. After all, it's a manga from Japan, so their thinking is somewhat limited. However, the author handled it very well; the female crew members are all clean and pure. If anyone sees any unclean crew members, come and scold me!
It looks alright; you could read it if you're looking for something to read. [Take a closer look]