Looking for a Chronological Novel, Where the Male Protagonist Travels Through Time and the Female Protagonist Is an Aborigine

I forgot which story it was, but the general content is that the male protagonist is a scientific research genius. He travels to the 1970s and 1980s, meets an indigenous female protagonist, takes her to take the college entrance examination, and develops computers and televisions for the female protagonist. Later, the leader asked the female protagonist for help and asked the male protagonist to develop a fighter jet for the female protagonist.