During a period in which Toei shifted from mass vendetta period dramas to yakuza films, Kato directed "Kutsukake Tokijiro yukyo ippiki," his masterpiece whose title became a byword for Tai KATO; "Brutal Tales from the End of the Edo Period" a realistic period drama about internal conflict in the Shinsengumi (a special police force at the end of the Tokugawa Shogunate); and "Meiji kyokakuden sandaime shumei" (The Story of a Meiji Knight, the Third Generation), which presented life in the Japanese Mafia with a unique sense of beauty and lyricism and greatly influenced later yakuza films.
東映が集団抗争時代劇から任侠路線へと移行する時期には、タイトルが加藤泰自身の代名詞ともなる最高傑作『沓掛時次郎遊侠一匹』をものにし、新選組内部の抗争を描いたリアリズム時代劇『幕末残酷物語』などを撮り、そして、やくざの生きざまを独特の美意識と叙情で描いてその後の任侠映画に多大な影響を与えた『明治侠客伝三代目襲名』を監督する。