He is best known for co-writing screenplays for a number of films directed by Akira Kurosawa, including Ikiru (1952), Seven Samurai (1954), Throne of Blood (1957), and The Hidden Fortress (1958).

[3] Film critic Donald Richie regarded him as the "humanist" among Kurosawa's writers.

[4] Writing credits other than for Kurosawa films include Heinosuke Gosho's Where Chimneys Are Seen (1953), Koji Shima's Warning from Space (1956), Bin Kato's Heiji Zenigata: Chase the Demon Lantern (1958), Tora!

[2] In 2013, Oguni and his frequent collaborators—Kurosawa, Shinobu Hashimoto and Ryūzō Kikushima—were awarded the Jean Renoir Award by the Writers Guild of America West.

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