Nobuyuki is the father of Tenchi Masaki. He works as an architect.

He appears to be the main source of money for Tenchi and the girls while they are on Earth.

In Tenchi Muyo! Ryo-Ohki, Nobuyuki is only a minor character, a distant descendant of Yosho (Katsuhito). Originally, he and Tenchi lived in the city where he would work and Tenchi would go to school. But after Ryoko was awakened, Nobuyuki saw Tenchi with her and was surprised that Tenchi had a girl in his room. Nobuyuki attempted to record their private session, but then Ayeka arrived and Nobuyuki was miniaturized along with the house by Ryoko while escaping from Ayeka.

Afterwards, the house was permanently relocated next to the Masaki family shrine and Nobuyuki eventually moved back into the city living in an apartment with an old friend of the family, Rea Masaki. He and Rea became engaged and at the end of the series they were married.

Before the ceremony, Tenchi at first was angry when he found out that the story he was told about how his late mother Kiyone died was fictitious. Eventually Tenchi and Nobuyuki talked and Tenchi apologized for his earlier behavior and chose to accept his father's new wife Rea, as she had been more of a mother figure to him than his real mother and having her around won't be any different. Nobuyuki admitted that it was because of that fictitious story that they hesitated to tell him about the truth behind Kiyone's death or that Kiyone was also a prankster.

Due to his Juraian heritage and training (enhancement) at the Galaxy Academy, Nobuyuki has lived longer than any normal human, and is currently around two hundred years of age.

(Source: Wikipedia)