Nao Kitazawa, 34, leads a busy but fulfilling life as a doctor at a women's clinic and as fiancee to an elite psychiatric physician, Yuchi Ihara. With their wedding day a month off, Nao is preparing to move into a new home when she meets Shinji Mamiya, a struggling writer who works part-time as a mover and falls inexorably in love with him. The fateful encounter compels Nao to follow her heart and experience true love.

Overwhelmed by Nao's passion, Shinji soon falls for her as well, but their budding romance is threatened by the tragic discovery that Nao has early onset Alzheimer's. What unfolds is a story of pure love. As Nao's symptoms worsen, Shinji spends the next ten years giving Nao mental and health support even as she begins to lose the precious memories they both shared.