九州にある小中高一貫校の私立「上園学園」z90;物語は入学早z93;にして衝撃的な出会いを果たした上下山虎子ら4人の女の子を中心としてz89;個性的なクラスメイトらを交えた破天荒な学園生活をコメディチックに描いていくz90;

Hyakko takes place in the high school division of Kamizono Academy (上園学園 Kamizono Gakuen?), a fictional gigantic private institution located in Kyūshū, Japan, in which the motto is "to bring up talents of students in all departments and fields". Its storyline focuses on the comedic school life of the four main heroines, Torako Kageyama, Ayumi Nonomura, Tatsuki Iizuka, and Suzune Saotome. As the plot progresses, Torako and her friends gradually begin to learn and interact with their classmates in Class 1-6, in which each student has unique and extraordinary personality.