Medaka Kurokami is, in the truest sense of the word, perfect. Beautiful, intelligent, and athletic, Medaka's dream is to make others happy. So when she runs for Student Council President of the prestigious Hakoniwa Academy, winning the election with 98% of the votes is only to be expected. The very first thing the boisterous new president does is set up the "Medaka Box," a suggestion box allowing students to submit any kind of request for assistance. Together with the cynical Zenkichi Hitoyoshi, her childhood friend who has been strong-armed into helping, Medaka fulfills these requests at a ridiculous rate. For every job completed, she adds flowers to the student council room, with the aim of filling the entire school. However, the two are about to find out that helping others may be a lot harder than they think as they begin to uncover a devastating plan centering on the academy and even Medaka herself!

After the defeat of Myouri Unzen at the hands of Medaka Kurokami and her Student Council, peace has returned to Hakoniwa Academy—at least, for a short while. Soon, Medaka, Zenkichi Hitoyoshi, Kouki Akune, and Mogana Kikaijima find themselves wrapped up in another sinister scheme, known as the "Flask Plan," led by the school's principal himself. However, the council's first problem is to deal with a whole new group of superhuman students calling themselves the "Thirteen Party," led by the egotistical but powerful Oudo Miyakonojou. With the mysterious Flask Plan, Oudo's tyranny, and the resurfacing of an old enemy, the state of Hakoniwa Academy is far from tranquil, and Medaka and her companions have their hands full as things only get a lot more abnormal.