To Handa is a dhampir, born to a human father and a vampire mother. He serves as an officer in Shin-Yokohama's Vampire Control Division, operating under Vice Captain Hinaichi and alongside Captain Hiyoshi, monitoring and regulating vampire activities.

He attended high school with vampire hunter Ronaldo. His primary motivation stems from his mother Akemi Handa's intense admiration for Ronaldo, whose autobiography series she avidly follows. This fuels To Handa's distress and a persistent fixation on exposing what he perceives as Ronaldo's undesirable traits. His animosity borders on obsession, filling his personal space with Ronaldo-related posters and merchandise as constant reminders of his goal.

To Handa frequently employs tactical methods to unsettle Ronaldo, notably exploiting Ronaldo's extreme phobia of celery. He uses celery stalks to block Ronaldo's apartment access and recruited fellow officer Sagyou to dress as a celery stalk during operations. He also conducts surveillance on Ronaldo, monitoring his apartment to collect potentially compromising information.

Despite his antagonism toward Ronaldo, To Handa develops an unexpected camaraderie with the vampire Draluc. He considers Draluc a close friend based on their shared enjoyment of Ronaldo's discomfort, leading them to collaborate on schemes aimed at uncovering Ronaldo's secrets or causing him minor inconveniences. Their interactions involve comedic attempts to investigate Ronaldo.

His family background includes his mother Akemi, whose enthusiastic fandom fuels his actions, and his father, who is less prominently featured. His maternal dhampir heritage influences his role in the Vampire Control Division.