Death Note’s Ryuk won’t be featured as a playable character in Jump Force because “he’d be too strong.”
Jump Force was announced at E3 2018 and if you watched the reveal trailer, you’ll have spotted Death Note’s Light Yagami and Ryuk at the end, but producer Koji Nakajima has confirmed that the Ryuk will not be a playable character.
“Ryuk from Death Note isn’t a playable character,” Nakajima confirmed in an interview with Bahamut via Silicon Era, “because if he writes names into the Death Note, people die, right? He’d be too strong.”
Source: IGN.com Jump Force: Death Note's Ryuk "Too Strong" to be Playable Character