I Married the Ghost Bride from the Start, and Hit the Jackpot

A modern-day corporate drone transmigrates to a parallel world, reborn in the body of someone who died in a fall during an outing. While spending the night in the mountains, he encounters a ghostly wedding procession. The ghostly groom is killed by one of his companions, and the ghostly bride is about to slaughter them all. With his life hanging by a thread, he does something that betrays eighteen generations of his ancestors: he takes the ghostly groom's place and prepares to exchange wedding vows with the ghostly bride.