At Hakkao Academy, there is no Yumeko. One year before Yumeko transfers to the school, an utterly ordinary girl, Saotome Meari, enrolls at Hakkao Academy. However, what awaits her is the school's insane rules and a baptism of gambling. This is a prequel to Kakegurui, a story about another "outsider". Saotome Meari's "Kakegurui" pairs her with Yumeko as twins.