...No. Shiki is past Ziggy. Void is Ziggy's son.

Bro did NOT read the manga

Well when Ziggy was Shiki he banged Rebecca who become pregnant after the whole bomb shit 20,000 later Ziggy time travel in edens one where Void who is now Ziggy son living as AI, it fused with edens one AI and go on a path to kill mother

In short Void is the son of Shiki and Rebecca from alternative timeline

Void is the son of an alternate time line shiki and Rebecca that are from a time where they tired to stop a massive explosion that time lines shiki was turned into ziggy in a far of future and Rebecca wasn’t able to be saved yet she carried the unborn void whose consciousness was turned into an a.i which became void and they sent ziggy back in time using Rebecca’s time travel ether gear abilities where ziggy not only created granbell but the four stars and somehow found his past self whom he raised as his grandson until one of Rebecca’s time jumps sent them to a world where ziggy was controlled by void and then when they entered universe zero void now has a body which resembles his father shiki but he has both shiki and Rebecca’s powers

She activated a shield that reflected all the blasts back at him