Everything was going well—love, work, life. Until that day arrived. Miyata Aiko works at an apparel store. Though she lost her parents young, she’s spent her days happily surrounded by her kind older sister, Saeko, and childhood friend Yoshimura Yuma, a doctor. Aiko is dating Yuma, but hasn’t had the courage to tell Saeko. As her 25th birthday approaches, Aiko wonders if Yuma might propose, but on her way home one day, someone pushes her down a flight of stairs. She loses consciousness, and when she wakes up… Yuma is married to Saeko. On top of that, Aiko loses a major career opportunity. From that moment on, she’s swept into a tragedy beyond anything she could have imagined. Behind it all, a certain person’s hidden motives begin to surface… (Source: IrozukuSubs) ~~ Adapted from the manga series "Watashi no Kare ga Ane no Otto ni natta Riyu" (私の彼が姉の夫になった理由) by Mio Serina (美桜せりな).