That does sound like a compelling idea. It would be like a inverse of Asa maybe. When Asa was about to die in the beginning of Part 2, she said she wished she lived a little bit more selfishly and it is manifesting itself as Yoru having fun with Denji and causing chaos. Asa now realizes that maybe this isn't wanted she wanted and this new character could be the inverse. This character is trying to help everyone and maybe Death promised to help them in their goal before they died as well.