Watashi no Kare ga Ane no Otto ni Natta Riyuu

"Both my career and my love life were going so well...but it all fell apart on my 25th birthday, the day of that fateful incident." Aiko Miyata may have lost her parents at a young age, but she still grew up with plenty of love in her life from her kind older sister Sae and her doting doctor boyfriend Yuuma Yoshimura. Her happy life seems to be headed toward pure bliss, with Yuuma poised to ask her a very big question at her birthday dinner, when out of nowhere she gets stabbed by a hooded figure. From that day onward, Aiko finds herself mired in a tragedy of epic proportions...! This psychological thriller blurs the lines between love and hate as Aiko struggles to stay afloat. Hard to watch, but even harder to look away... How much can you handle? (Source: MangaPlaza)