From Okazu:

The story follows Shijou Fumio, whose life radically changes when her mother dies. Although they lived in poverty, it turns out that Fumio's father was unbelievably wealthy and her older brother, who had been kept by the grandmother who threw her pregnant mother out, now wants Fumio in his life.

Fumio transfers to St. Michael's and instantly, due to her good grades, excellent athleticism and general down-to-earth qualities, is immediately escalated to the rank of star of the school, nicknamed "The Saviour." She joins Saiki Kazune, know as "Oscar-sama," and Sarashina Yuzuko called, hysterically, "the Colobockle."