Nobuyuki Masaki (柾木 信幸, Masaki Nobuyuki) is the father of metaseries protagonist Tenchi Masaki who works in the city as an architect. Although he has shown that he is less responsible than his son, Nobuyuki does care deeply for Tenchi, and after losing his wife, Nobuyuki worked hard to raise him. He is also a voyeurist/peeping Tom and tries to encourage Tenchi to be more sexually active and not as shy towards women (only for his efforts to have the opposite effect). Nobuyuki has appeared in all Tenchi Muyo! series. In every series, Nobuyuki designed and built the house that Tenchi and his extended family live in.
Nobuyuki is a direct descendant of Yosho Masaki Jurai, the Prince of planet Jurai, offspring from his marriage with his first wife Kasumi (he has addressed Yosho/Katsuhito both as "father" and as "grandfather," but the exact nature of the relation, how many generations separate them, has yet to be verified). In the Light Novels, Tennyo reveals that Nobuyuki is one of the few Masaki family members to remain on Earth, and not join the GP or other branches of the Academy. She also gives an age for Nobuyuki of roughly 120.
Due to his (diluted) Juraian heritage, Nobuyuki has lived much longer than any normal Earthlings. However, unlike most in Masaki family, it has been explained that he has never left Earth and has had no body enhancements, meaning it will be a shorter life than other members of his family. Nobuyuki met Katsuhito's daughter Kiyone Masaki when Nobuyuki was a young boy. Kiyone seemed to love teasing him, much to the despair of those around them. She nicknamed him "Nobu." Eventually, the two fell in love and married, which the Masaki Village wasn't too keen on, apparently. In time, they bore two children, Tennyo and the main protagonist Tenchi. However, Kiyone died when Tenchi was still a young boy and Tennyo left Earth shortly after. He tends to conceal the fact he looks like he's still in his 20s, appearing to be in his mid to late 40s. Though he allowed his true appearance to show during his wedding to his second wife, Rea. Originally, he and Tenchi lived in the city, where he would work and Tenchi would go to school. But after the space pirate, Ryoko was awakened, Nobuyuki saw Tenchi with her and was surprised that Tenchi had a girl in his room. Nobuyuki attempted to videotape their 'private session,' but the Juraian Princess, Ayeka, arrived in her ship, and Nobuyuki was captured along with the house by Ryoko while escaping from Ayeka.
Afterward, the house was permanently relocated next to the Masaki family shrine, and Nobuyuki soon moved back into the city, living in an apartment with his assistant, Rea. He and Rea became engaged and married.
Before the ceremony, Tenchi was initially 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 reveals that he's long-since accepted his father's new wife, as she had long been more of a mother figure to him after his birth mother, Kiyone, had died, and having her around wouldn'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.
- The name Nobuyuki means "trust" (信) (nobu) and ""happiness, good luck (幸) (yuki).
- Nobuyuki's surname Masaki means "straight grain, spindle tree, (kokuji)" (柾) (masa) and "tree, wood" (木) (ki).