Soby, formally named Sewashi Nobi, is Nobita Nobi's great-great-grandson from the 22nd century. As a direct descendant, his existence depends directly on the outcomes of Nobita's life choices. Witnessing Nobita's troubled circumstances leading to a financially burdensome future for their family motivates him to travel back in time. He brings Doraemon, a robotic cat caretaker, to alter Nobita's trajectory and prevent inherited debts. Physically, Soby shares strong resemblances with other male Nobi family members, particularly Nobisuke (Nobita's son), characterized by fair skin, dark hair, and large eyes. His appearance varies across adaptations: early portrayals show him in red jumpsuits wearing glasses, while later iterations, like the 2014 film, feature teal or white attire with a turtleneck, omit glasses, and sometimes depict his hair with a ginger tint. Personality-wise, Soby exhibits greater confidence and technological proficiency than Nobita. Though academically average like his ancestors, he displays athleticism and a proactive, resourceful nature. His actions stem from familial responsibility, contrasting with Doraemon's initial hesitance. He possesses a pragmatic understanding of temporal mechanics, acknowledging that altering Nobita's future may not erase his own existence but could alleviate his family's hardships. His family includes parents—a mother resembling a futuristic Tamako (Nobita's mother) and a father identified as Nobita and Shizuka's great-grandson. He regards Nobita's parents as his great-great-great-grandparents, highlighting his multigenerational commitment to reshaping their shared destiny. Within the film narrative, Soby plays a pivotal, proactive role. He imposes a behavioral program on Doraemon, binding the robot's return to the future to successfully improving Nobita's life. This program activates automatically upon Nobita achieving a stable future, mandating Doraemon's departure. His actions establish the core conflict and emotional stakes, framing Nobita and Doraemon's relationship while setting conditions for their separation and reunion. Regarding temporal continuity, Soby proceeds from the understanding that altering Nobita's path won't prevent his own birth but will mitigate the family's hardships. This perspective indicates a belief in causal loops or self-correcting timelines. His appearances or development in other media beyond the film, like spin-offs, OVAs, or alternate seasons, are limited to this narrative. Details of his 22nd-century life outside his mission to aid Nobita remain focused on his role as the initiator of these events.