Suiu Fujiwara is a second-year graduate student at Saitama University, specializing in biology with research focused on aphrodisiacs and the biological mechanisms of love. She works at the university's Biological Sciences Research Center with her long-term boyfriend, Chris Florette. Suiu possesses hip-length jet-black hair featuring bangs covering the right side of her face, with shoulder-length strands framing either side. She has dark gray eyes, full pink lips, and a distinctive mole on the lower left side of her lips. Her figure is noted for large breasts. Her personality is bold, flirtatious, and unapologetically expressive. She openly discusses attraction and biology without hesitation and frequently engages in physical affection with Chris, such as caressing him. She exhibits a playful and confident approach to her research and relationships. Suiu and Chris are an established couple with a notably strong and stable romantic bond, contrasting with the main protagonists' tentative relationship. Their interactions demonstrate mutual comfort and high intimacy, consistently corroborated by biological measurements like oxytocin levels, positioning them as a "power couple." In the second season, Suiu and Chris directly challenge the main characters, Yukimura and Himuro, on their scientific methodology for proving love. They argue love transcends purely data-driven analysis, advocating for its abstract and experiential nature. To support this, they volunteer for oxytocin-level testing, using close physical contact like snuggling and verbal affirmations to induce measurable responses. During these experiments, Suiu and Chris consistently register higher oxytocin levels than Yukimura and Himuro, questioning the latter's rigid approach. Beyond challenging the protagonists' research, Suiu participates in social activities like group dates and the Saitama University festival alongside Chris and other characters. Her presence juxtaposes this intuitive understanding of romance against the main couple's analytical struggles.