七人のナナ

On the last Valentine's Day before her high school entrance exams, Nana Suzuki tries to build up the courage to confess to her longtime crush. However, when her chocolates are accidentally ruined, she rushes back to her house to make more—not realizing that the microwave has been turned into a strange invention by her grandfather. Suddenly, six additional copies of Nana appear, each possessing their own extreme personality and a crystal that grants them magic powers!

With her plans ruined, Nana vows to confess to her crush in her first year of high school. The only problem is that her crush is top student Yuuichi Kamichika, and following him to his elite high school will mean that she has to hit the books. With six new allies to help her, Nana begins to prepare for anything that the exam season might throw at her.

(Source: MAL)