Suginami appears across multiple Da Capo timelines with distinct incarnations. In the original timeline, he attends Kazami affiliated junior high class 3-1 alongside Jun'ichi and Nemu Asakura. Though an excellent athlete, top student, and possessing good looks, his eccentric and disturbing personality causes most peers to keep their distance. He frequently teases Mako Mizukoshi and drags Jun'ichi into various schemes. Suginami often gives Jun'ichi unconventional, mischievous advice on relationships with female classmates. An air of secrecy surrounds his actions and motivations, cementing his reputation as the school troublemaker. Fifty years later in the Da Capo II timeline, a character identical in appearance and personality emerges as a classmate and self-proclaimed friend of protagonist Yoshiyuki Sakurai. This version similarly excels academically and athletically but exhibits a penchant for involving Yoshiyuki in troublesome scenarios, creating a "fatal friendship" marked by constant chaos. He develops an interest in paranormal investigations, frequently testing the Student Council's patience with his schemes. Despite the physical and behavioral similarities to the original, this Suginami is considered a descendant lacking his predecessor's memories. Within Da Capo III, another iteration attends Kazami affiliated junior high as Kiyotaka Yoshino's classmate and a member of the informal newspaper club. Retaining characteristic intelligence and mischievousness, this version displays increased maturity. He actively identifies students' hidden talents or specialties, often sparking events of varying scales. His collaborations with Ricca Morizono on projects—like featuring cats and dogs in publications—unexpectedly boost the club's popularity. While maintaining a good relationship with Kiyotaka, he frequently causes complications for him, later transitioning into an informant role for the newspaper club. Across all incarnations, Suginami consistently demonstrates intelligence, athleticism, and a peculiar personality that isolates him socially. His actions consistently drive plot developments through manipulating other characters and engaging in unconventional activities.