Shinichi Nagakawa and Yuuki Sanada die in the same accident and are offered seven more days of life on one condition: when the time runs out, one of them must die for good. A god also ties their two lives together, so they share each other's pain and emotions and cannot step away from one another without both dying. Two strangers now have a week to live in lockstep, each of them hoping to be the one who stays.