Kanako Nagai is a high school student with dark brown hair, striking aubergine-colored eyes, and a petite stature of 1.57 meters. Her measurements of 88-66-86 and weight of 49 kilograms reflect a lean build, paired with blood type AB and a birthday on June 26.

Her name originates from the kanji 加 (*ka*, "add/increase"), 奈 (*na*, "apple tree"), and 子 (*ko*, "child"), while her surname Nagai combines 永 (*naga*, "eternal") and 井 (*i*, "well/mine shaft"). Kanako is characterized as a voracious eater who actively participates in baseball, suggesting a dynamic tension between her hearty appetite and athletic pursuits—potentially framing baseball as a counterbalance to her dietary indulgences.