Sayaka Dejima is the personal maid to Aria Shichijō within the Shichijō household. She maintains a polished, typically deadpan professional demeanor during her duties, though occasional bursts of overexcitement reveal immature behavior reminiscent of Naruko Yokoshima. Her speech remains extremely polite and controlled.

Physically, she possesses long dark hair, usually tied up, and dark eyes. She wears contact lenses and most often appears in her maid uniform. For outdoor activities like hiking, she switches to situation-appropriate attire and frequently styles her hair in a ponytail.

Her professional skills surpass standard maid duties, excelling at cooking, cleaning, laundry, driving various vehicles (including customized limousines), skiing, swimming, and identifying edible plants in the wild. She adapts competently across diverse circumstances required for Aria's care.

Despite her professionalism, Sayaka exhibits significant perverted tendencies. She openly acknowledges sexual experience and expertise in practices like bondage and domination. She harbors a deep, often inappropriate obsession with Aria, sometimes watching her sleep—behavior unsettling to others, though Aria appears unconcerned. She possesses a fetish for unwashed clothing and items touched or worn by Aria, particularly underwear, and serves as the keeper of the key to Aria’s chastity belt.

Her interactions with Takatoshi Tsuda involve mutual respect, though she occasionally implies interest in a sexual fling. She once restrained him in bondage ropes after he accidentally encountered Aria showering. Her relationship with Aria borders on stalking, fueled by intense devotion she describes as nursing a massive love.

Additional details note her recent hiring coincided with Aria’s second year of high school, her reporting structure under head butler Hashitaka-san, and the meaning of her surname kanji: "Exit/Protrude" (出) and "Island" (島).