Yuko Takayanagi

Yuko Takayanagi is Shin's older sister and she belongs to a cheer group. She forced him to join her group so it can count up to two members. She consider herself a rival of the girls in the cheerleader group and want to use her brother to take revenge over them in order to disband them (and to make them cry), so her cheer squad could come to see the light. She the one who prepared the breast lactation medicine that Shin had to use in order to accomplish her humiliation plan.