From MangaHelpers:
One day, a radio personality named Yuiko and a hairdresser named Chiaki meet by chance. However, they are both more than what they seem. Yuiko has the mark of a knot on her chest, signifying that she is the dangerous and powerful woman who comes again as each cycle of the Earth approaches disaster, and time and space begin to warp. It is said that she must be killed, or it could mean the end of humanity. Those who seek to kill her are known as engravers, and the one who takes her life will be granted a single wish. Chiaki is a reincarnation and an engraver, but he is determined to protect Yuiko and find another way to stop the world from spiraling into chaos.