Silk and Vivienne's friend and classmate. Tsubomi is a cosplayer by hobby, so when she realized that she too was a giant heroine, she took the idea without feeling any shame or embarrassment. However, because of this attitude, she was basically useless, since the source of their strength comes from being thoroughly embarrassed and projecting that emotion into an energy that can defeat their giant adversaries. Even after learning this, Tsubomi is not fazed and enjoys her new profession as a heroine and still manages to hold back the many giant monsters they encounter by tricking them instead of using brute power. It was Tsubomi's idea to go by the name "Ultimate Girl." She is called "Loli" by the press, due to her underdeveloped chest.