The protagonist, Yunoki Mio, is a student at Private Lady's Academy Reisei, the president of the student council, and a member of a tennis club. She spends her busy but joyful days with childhood friend Ayukawa Rinka, who aspires to become a professional tennis player; cousin Ikoma Yui; and Asahina Konomi, a junior on student council who adores her.

With both of her parents being doctors, Mio wants to pursue medicine in the future too. Her parents work far away in foreign lands and return home only a few times a year. However, the protagonist is not lonely because Toya Shiori, a live-in maid, is also present at the home. Mio and Shiori think of each other as sisters—they are like a family.