Jump Force Ad Seemingly Reveals Jotaro Kujo, Dragon Quest Anime Hero As Playable Characters - Game Informer

They haven't been officially revealed, but it seems they're part of the cast.

JUMP FORCE - Official NEW Characters & Gameplay (2019)

Jump Force Ad Seemingly Reveals Jotaro Kujo, Dragon Quest Anime Hero As Playable Characters

Jump Force - Game Informer

News - June, 2022

A Short Bio Of Every Jump Force Character - Game Informer

Jump Force Game Adds JoJo's Bizarre Adventure's Jotaro, DIO - News - Anime News Network

Jump Force - Jojo's Bizarre Adventure Character Reveal Trailer

JUMP FORCE - Official NEW Characters & Gameplay (2019)

Dai from Dai no Daibouken and Jotaro from Jojo's Bizarre Adventure may have been leaked for Jump Force by Bandai Namco

Jotaro Kujo, DBX Wiki

Jump Force Jotaro and Dio Revealed in Weekly Jump

JUMP FORCE - Jotaro and DIO Character Trailer

Jump Force review: An ambitious brawler that suffers from something of an identity crisis

Dragon Quest's Dai confirmed for Jump Force