From the Start, I Had a Chainsaw and Ran Wild in Ancient Times

After countless hardships, Feng Ke finally passes the civil service exam and lands a government job. But on the very night he celebrates, he tumbles into an ancient mountain village with nothing but bare walls. He also gets a starving, gaunt younger sister, and a bizarre black hole. The black hole connects to the modern world, letting him reach in and pull things out. But what comes out depends on the modern-day situation at his current location. The first time he reaches in, he pulls out [three braised pork intestines]. His sister cries as she eats them. “Big brother, they’re so delicious!” The second time, he pulls out [a super-thin, invisible wolf-tooth mouthguard], turns it into a slingshot, and gives it to a hunter. It’s hailed as a divine weapon! The third time, he pulls out [a roaring chainsaw], and then... the whole story takes a strange turn!