Karen Fujisaki is the petite treasurer of Seifu High School's student council, characterized by her yellow or blonde twintails extending past her hips and brown eyes. She consistently appears in her school uniform with stockings. Her defining trait is an intense, perverted devotion to student council president Ui Wakana, driving significant antagonism and frequent conflicts with Hayato Izumi due to murderous jealousy over his relationship with Ui. This jealousy reportedly mellows in later chapters. One incident exemplifying her obsession involves a severe nosebleed triggered by seeing Ui's mother in a school uniform. Her name "Karen" combines the characters for "possible" and "sympathy," while "Fujisaki" translates to "wisteria blossom."