As a first-year student of the renowned Hyakkaou Private Academy, Mary Saotome knows her future is set for a one-way cruise to the top...

That is, until an encounter with an old-classmate-turned-housepet throws the newbie princess into the world of gambling! Can a normal girl like Mary make friends and survive debtless through only wit and luck? Find out in this prequel to the mega-popular Kakegurui!