Raised by a single mother, Kanzaki Sena is a gentle-hearted, hard-working OL at an advertising agency. She lives with her fiance and co-worker, Shindou Kouki, who comes from a line of important politicians. His family, against their engagement, pushes him to marry another woman with better family connections. This strains Sena and Kouki's relationship and they begin to grow distant. Around this time, Sena meets a mysterious janitor named Moriyama Seiji and is drawn to his darkness. One fateful evening, an incident occurs that changes the destinies of all 3 characters.
Sena Kanzaki, raised in a single-parent household, is a kind-hearted and hardworking girl. She works as a temporary employee at a major advertising agency. She has been dating Mitsuki Shindo, whom she met at work, for three years and they are currently living together. She is engaged to him, as he is the third-generation son of a politician, and they were on the verge of a marriage that everyone would envy. However, Mitsuki's family opposes the marriage and pressures him into a politically motivated marriage. An uneasy atmosphere begins to hang between the two of them. At this time, Sena meets Seiji Moriyama, a gruff janitor. He is a man with a mysterious aura, as if he has given up on life. He has a heart condition and only a short time left to live unless he receives a transplant. And then, a twist of fate occurs. The destinies of these three people are about to change dramatically.