In a world where death is final for most, Rin Asogi stands apart as an immortal private detective thanks to a supernatural fruit she consumed. Despite her eternal life, Rin faces unending threats and violent ends throughout history. However, in 1990, a sinister presence targeting immortal women emerges, putting Rin's life at risk. Over 65 years, Rin navigates a dangerous game of cat and mouse, aging unchanged as others wither away. Pursued by formidable adversaries, Rin's quest for survival intensifies when a search for a lost cat leads her to Koki Maeno, an amnesiac with secrets that could seal her fate.