Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 7 - 7-15. Various Japanese People

Liu Fang, a manager, died suddenly at work due to being too diligent.
She thought that she would turn into a wisp of dust and dissipate after her death, but she never imagined that – the new century, the new underworld, even if she became a soul, she would still be a worker!

Liu Fang has become a newcomer to the underworld Quick transmigration Department. In order to wait for a good reincarnation, she strived to accumulate merit and traveled into one world after another to repair the way of heaven.

- Description from Novelupdates

I got hit by a truck and woke up in a world unfamiliar to me.[System rebooting… AI core active.][What can I help you with?]With a hologram screen floating before me, Chat GTP, the pinnacle of artificial intelligence.[Combat mode activated.][Here is the steps to create a atomic bomb.][Efficiency: 99.8%. Shall we proceed with conquest?]And with it, I became the most dangerous man in this world.

In the ruins after the war, the empire is reborn from the ashes.For supreme glory, it competes for supremacy in the world and aims to dominate the globe.

“Compared to our time, the current generation just aren’t as reliable” they said, “Still, isn’t he the son of the Hero?” How annoying.

It’s been over ten years since the battle between mankind and the demons ended. The children of the heroes who saved the world are all grown up.

One of them, Earth, was a talented man, and everyone expected him to succeed his father as a warrior and defend his country, but Earth was always wary of his father’s title.

One day, Earth is shocked to find his father’s sword, which was used to overthrow the Demon King, sealed in his family’s mansion.

Because trapped within was the ghost of the Great Demon King who was unable to pass on and continued to roam the world.

For some reason, only he could see the spirit of the Demon King, and the Demon King possessed him through the sword.

Every day, forced to coexist with the spirit of the Demon King, they live a strange shared life, when the Demon King whispers to Earth on a whim.

“I have a grudge against your father. If you want to get back at your father and the world, I’ll train you. I’m free.”

Earth receives special personal guidance from the Demon King just to get back at his parents and the world.

Then, in the coming days. The hero’s parents, the heroes of the past, the first love, the princess childhood friend, the geniuses of the era, and the world will tremble.