Toshika Jin is Kaito Jin's relative, sharing his family name and appearing in a parental or guardian role, though their exact familial connection is unspecified. Originally from Tokyo, she relocated to Nagoya before the series begins. This move from the capital to Aichi Prefecture resulted in a complex relationship with regional identity. She skillfully navigates Nagoya culture, retaining aspects of her Tokyo origins while developing appreciation for local customs. This places her perspective between Kaito's initial Tokyo-centric views and Monaka Yatogame's strong regional pride.

Her characterization includes collecting security devices as a hobby. She interacts with primary characters Monaka Yatogame, Mai Tadakusa, and Yanna Sasatsu. Across the anime's seasons, she maintains a consistent presence as part of the supporting cast, with no documented significant alterations to her core personality or circumstances. Her role provides contrast to both recent Tokyo transplants like Kaito and lifelong Nagoya residents, embodying moderate cultural adaptation. The later introduction of characters from other regions like Osaka and Kyoto further contextualizes her intermediate position regarding regional identity.