As she was busy bullying the honour student with the power of light magic, Maria Campbell, along with her friends, the fifteen year old daughter of a Duke Katarina Claes suddenly hit her head and remembered her previous life.

Thanks to those memories, Katarina realized that she was actually the villainess of an otome game that she had played in her previous life, with a struggle to avoid the destruction flags that would lead to her doom awaiting her…

Except, there's not even a year left before her destruction end!? The story of Katarina, who is on the verge of her demise, begins now…!

• Note: This is a "What-If" story to the original Otome Game no Hametsu Flag shika nai Akuyaku Reijou ni Tensei shite shimatta... where Katarina receives memories of the real world from the moment the otome game starts when she's 15, and not from her childhood like in the original work.