He successively worked on screenplays for major projects including "Mahiru no Ankoku" (Darkness at Noon), "Harikomi" (Stakeout), "Zero no Shoten" (Zero Focus), "Seppuku" (Harakiri), "Kiri no Hata" (Flag in the Mist), "Joi-Uchi" (Samurai Rebellion), "Shiroi Kyoto" (The White Tower), "Nihon no Ichiban Nagai Hi" (Japan's Longest Day), and "Nihon Chinbotsu" (Japan Sinks); and was highly praised for his ability to write logical and solid pieces.
代表作に挙げられる『真昼の暗黒』、『張込み』、『ゼロの焦点』、『切腹』、『霧の旗』、『上意討ち』、『白い巨塔(映画)』、『日本のいちばん長い日』、『日本沈没』などの大作の脚本を次々と手がけ、論理的で確固とした構成力が高い評価を得る。