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.

Jotaro & DIO 'Jump Force' Roster Addition

Jotaro and Dai leaked as new additions to Jump Force

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

JUMP FORCE - Official NEW Characters & Gameplay (2019)

Bandai Namco Adds Legendary 'Dragon Quest' Character To 'Jump Force' Roster

Filtrados Jotaro Kujo (JoJo) y Dai (Dragon Quest) como personajes de Jump Force

A Short Bio Of Every Jump Force Character - Game Informer

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

Dai from Dragon Quest officially confirmed for Jump Force - KeenGamer

Jotaro - Jump Force Guide - IGN

Jump Force Advertisement May Have Accidentally Revealed Dai and Jotaro As Playable Characters