Masamune Usami

Usami is a member of S4 or Shooting Star Subaru-Sama. She is shown to have considerable leg power which she uses in the form of kicks. She blackmailed Kinjirou, with the picture of him and Subaru on a mock date, to be her boyfriend up until the end of their school fair. Kinjirou accepted because of the condition that she will not spread the photo with Subaru and Kinjiro going out together. However she later becomes friends with Kinjirou and the others and is implied to have developed a crush on Kinjirou. Her name is noted to sound similar to the Japanese word for rabbit (ウサギ - Usagi) which becomes the source of Kinjirou's nickname for her; Usamin, her own nickname for him is "stupid chicken".

(Source: Wikipedia)