Shinobu Nakamachi leads the Nakamachi Circus with passion despite crippling financial hardship. His lifelong dedication to circus performance has left him fourteen months behind on rent for the circus warehouse. Confronted by landlords urging him to abandon the circus for conventional work, Shinobu reacted with intense anger, overturning a table and fiercely defending his life's work, revealing his volatile temperament and unwavering devotion.

He is the widower of Fusae Nakamachi, who died during a circus performance, deeply impacting him and his family. His two sons are Noriyuki "Nori" Nakamachi, the reliable older brother figure, and Hiroo "Hiro" Nakamachi, the younger son. Together they form the core family of the circus.

Facing dire financial strain, Shinobu, Nori, and Hiro devised schemes to generate income to sustain the circus. Their situation shifted when Masaru Saiga visited and persuaded Shirogane to join their troupe, integrating Shirogane into the circus, altering its path and connecting Shinobu to larger events.

His name "Shinobu" combines the characters for "trust/believe" (信) and "man/husband" (夫), while "Nakamachi" derives from "relation/relationship" (仲) and "town/village" (町).