Doomsday Rebirth: Slaying My Enemies from Two Lifetimes from the Start

After being reborn ten times, he finally obtained a System. From the start, he slew the enemies he had hated across two lifetimes. With the experience and memories of ten lives, plus the System’s powerful assistance, he found it easy to get by in the apocalypse. How did this apocalypse come about? What kind of conspiracy lies behind it? One day, he will uncover the truth! (Ruthless and decisive, not a do-gooder.)