He transmigrates to the world of One Piece and awakens the Undertaker System.
An Xi: "Whitebeard is a great guy, and he's so nice to talk to. He deserves a dignified funeral. For the sake of all the care points, leave it to me!"
An Xi: "System, System, tell me: if I dug a grave and prepared a coffin, joss paper, incense, candles, and all that beside the battlefield at Marineford, would they realize how wonderful it is to be alive and call off the fighting?"
System: "Probably not. They'd kill you first."
This novel and its characters are entirely fictional. Any resemblance is purely coincidental. Do not imitate.