I Was Raised By My Beloved Stepsister, And She Was Stolen Away By My Worst Friend...Nao Jinguji

Nao-nee and I aren't really siblings. She was the child of the woman my father remarried when I was a student. After our parents died in an accident, Nao-nee, who was much older, became my parent substitute. Life together was lonely, but I, who harbored romantic feelings for Nao-nee, also felt happy. One day, my best friend Yuzuru was whispering with Nao-nee, and as I approached feeling jealous, they skillfully evaded me. Then, at some point, Nao-nee started coming home late frequently...