Sewashi Nobi, hailing from the 22nd century, is the great-great-grandson of Nobita Nobi and Shizuka Minamoto. Tasked with altering Nobita’s fate to avert generational financial collapse and an ill-fated marriage, he deploys the robotic cat Doraemon to the past. Doraemon’s mission—to guide Nobita toward self-improvement—creates a causal loop, as Sewashi’s own existence hinges on this corrected timeline. Speculation suggests he might have manipulated historical records to validate Doraemon’s intervention while preserving temporal integrity. Physically mirroring Nobita’s son Nobisuke, Sewashi has fair skin, large eyes, and black hair, though his design shifts between adaptations. The 1973 anime portrays him in glasses and a red jumpsuit, while later versions favor teal or orange outfits. *Stand by Me Doraemon* aligns with manga depictions, giving him ginger hair. His wardrobe often incorporates futuristic elements like turtleneck jumpsuits or coordinated shirts and boots. Academically challenged like Nobita, Sewashi contrasts his ancestor through athletic prowess and a disciplined, earnest demeanor. He vigilantly oversees Nobita and Doraemon’s progress via future technology, partnering with Dorami to secure mission success. Despite his maturity, he shares Nobita’s dread of dentists, underscoring a familial weakness. His lineage traces to Nobisuke as his great-grandfather, though familial details are limited. His mother, glimpsed briefly, mirrors Nobita’s mother in appearance but adopts a futuristic style and calmer temperament. His father—Nobita and Shizuka’s great-grandson—appears in spin-offs such as *2112: The Birth of Doraemon*. Sewashi’s actions stem partly from centuries of inherited debt, compelling him to disrupt the cycle of hardship through Doraemon’s aid. Adaptive inconsistencies include the Indian dub labeling him Nobita’s grandson, creating narrative conflicts, and fluctuating temporal origins (21st or 22nd century) across anime versions, though the latter is standard. These variations highlight his adaptable portrayal while retaining his core function as a catalyst for Nobita’s transformation.