1st year, Class -13 15-16 AB Real Eater
She is a freshman of Class 1, later Class -13, and Zenkichi Hitoyoshi's best friend.
The comic relief of the series and the granddaughter of the Academy's principal. Shiranui is normally a very cheerful and hyper girl, but she has been shown to have a dark side and is brutally tactless. Despite her small size Shiranui has a very large appetite and is constantly seen eating, even while walking. She has a knack for finding clandestine information with ease, knowing about most things that would seem to be vague details, and is unusually perceptive. Shiranui harbors a hidden resentment against Medaka. Because of the antagonism that exists between them, Medaka initially asks Shiranui to become the Vice-President of the Student Council, though Shiranui refuses. She is also almost always seen hanging around with Zenkichi.