A new begining

After dying in a truck accident (classic isekai style), a cynical office worker is reborn not as a slime, a hero, or even a typical demon-but as the Demon Progenitor, the very first and the most ancient source of demonic power in existence. Now, trapped in the Tensei Shitara Slime Datta Ken universe long before Rimuru's rise, he must navigate his overwhelming abilities, chaotic demon subordinates, and the terrifying responsibility of being the origin of all demons.