Sayaka Watanabe is a 20-year-old college student living at Kawai Dormitory. Outwardly shy, cute, and innocent, this facade masks her true cunning, manipulative nature and enjoyment of causing trouble. She habitually leads men on only to abruptly end relationships, a pattern recognized by fellow residents. Her interactions with Mayumi Nishikino involve frequent unsolicited physical advances: groping Mayumi's breasts, attempting kisses, and initiating unwanted closeness, behaviors that escalate when Sayaka drinks alcohol. These actions fuel Mayumi's resentment while providing Sayaka amusement through provoked discomfort. Despite this, Sayaka demonstrates loyalty through her enduring friendship with Tsuneda Miharu, whom she protects and supports while masking her affection with indifference. They met in their second year of middle school when Sayaka intervened as upperclassmen harassed Miharu; the upperclassmen fled after witnessing Sayaka destroy a shed she'd been locked in as punishment, using a nail-studded baseball bat. This destructive response stemmed from a history of strict parental discipline involving shed confinement. The bat remains at the Kawai complex. Sayaka maintains meticulously applied makeup, and her appearance without it is implied to be significantly different. She possesses specific idiosyncrasies: an intense fear of rabbits and an interest in yaoi manga. Her nickname for Miharu is "Tsuneko," and their close middle school bond earned them the joint moniker "Nabe-Tsune." Sayaka attended an all-girls high school and expresses reluctance to engage with other women beyond Miharu, citing the effort involved. Sumiko, the dormitory manager, serves as the primary figure capable of curbing Sayaka's disruptive behavior through threats of punishment or direct discipline.