Konna Mirai wa Kiitenai!!

Kayo is a high school girl who is one day suddenly visited by her future 30-year-old self. Her future self begins to tell her that even at her age, she is still unmarried, and Shinnosuke, her childhood friend who she has a crush on, is already married to another woman. She realizes that she has to make Shinnosuke fall for him now to avert the worst future possibility. (Source: ANN)