Toto is a mysterious girl encountered by protagonist Shinichi during a 2710 school trip to reconstructed Nara City. She is an artificial being—an android or cyborg—created by a shadowy organization that relentlessly pursues her following her escape. This makes her a fugitive, hunted by agents including two brothers hired by the organization's president.

Her core journey involves experiencing the world beyond her confinement for the first time. She exhibits profound wonder and curiosity, especially towards everyday human activities and environments discovered at a festival. A key personal goal is her deep desire to see the ocean, representing freedom and new horizons. Her interactions with Shinichi, who aids her, drive her development; these moments showcase evolving emotional responses, shifting from innocence and joy to determination when facing pursuers.

Toto possesses physical capabilities exceeding normal humans, demonstrating agility and combat skill during escapes. She utilizes holographic technology to alter her appearance, a practical tool to hide her artificial nature that also touches on identity and perception. Despite her artificial origins, her nuanced facial animations convey genuine emotions, forging a meaningful connection with Shinichi within the story's short timeframe.

Her arc culminates in a confrontation with her creators' forces alongside Shinichi and the white deer. The resolution leaves her ultimate fate and the sustainability of her relationship with Shinichi, given their different existences, an open question.