One of his best-known roles was the dub voice of Darth Vader in Star Wars, on the series' home video releases and playing the title character Moguro Fukuzō in the original The Laughing Salesman.

After graduating from Tokyo Metropolitan University Jōnan Senior High School (in which he was also the supervisor of the school's volleyball team), he went on to graduate from the Meiji University Department of Political Science and Economics.

His breakthrough performance was the dubbing voice of Darth Vader in the Star Wars series.

He reprised this role for Star Wars: Episode III – Revenge of the Sith and a crossover appearance in Soulcalibur IV- notable because the game was originally in Japanese, meaning that Ōhira was Vader's "original" voice in the game, unlike with the films.

In addition, he was usually cast in either astringent villain roles or gag characters, such as Pete in Disney cartoons.