There's Must Something Wrong with My Undeads

After being expelled from the burial grounds, Heine summoned two undead creatures at home.
But soon he realized something off about his undead.
They seemed to know each other, chatting away inside his mind.
They had played a game based on this world and knew it better than he did.
Worse yet, they said his house was soon to be leveled, an imminent disaster...
Heine decided to pretend to be an aborigine who didn't know anything, just follow the instructions and be done with it.
…
Years later, when Heine ascended to the divine throne, he looked at his follower in disguise (forerunner in reality) and sighed.
"No more pretending, I'm also a transmigrator. I confessed!"
******
This book is also titled "Everyone's Gaming in Another World, Only I'm on a Fantasy Adventure."
This is a story about a necromancer and a group of Cynical transmigrators bumbling through the world with laughter and pretend.

Keywords: lighthearted, Western fantasy, single female lead, no system, not the fourth calamity.