Nobuyuki Masaki is the father of Tenchi Masaki in the Tenchi Muyo! series. He works as an architect in the city, a job that often keeps him away from home. After the death of his wife Kiyone, Nobuyuki dedicated himself to raising Tenchi on his own. He is a widower who deeply cares for his son, though he frequently displays a less responsible and more carefree demeanor than Tenchi. Nobuyuki has a playful and somewhat immature side; his main hobby is collecting shoujo manga, and he has a habit of being a peeping tom, often making inappropriate jokes or suggestions. He enjoys drinking sake and is known for his goofball nature.

Despite his flaws, Nobuyuki’s motivations center on supporting his son and maintaining a stable household. He serves as the primary financial provider for Tenchi and the girls living at the Masaki shrine while they are on Earth. In the OVA continuity, Nobuyuki is a minor character, a distant descendant of Yosho, also known as Katsuhito. He originally lived with Tenchi in the city, but after Ryoko awakened and Ayeka arrived, the house was relocated next to the Masaki shrine. Nobuyuki eventually moved back to the city and lived with an old family friend, Rea Masaki, whom he later married. This marriage initially caused tension with Tenchi, who was upset upon learning the story of his mother’s death was fictitious, but the two reconciled after an honest conversation.

Nobuyuki’s Juraian heritage and his training at the Galaxy Academy grant him an extended lifespan; he is around two hundred years old while appearing middle-aged. This longevity is a notable ability distinct from ordinary humans. He does not possess combat or supernatural powers prominent in the series, but his role is that of a grounding, occasionally comedic parental figure who provides emotional and material support to the main cast. His development centers on his relationship with Tenchi, moving from a somewhat distant, busy father to a more open and honest one who accepts his son’s acceptance of his new wife.