Tachihara Masaaki (立原 正秋, 6 January 1926 – 12 August 1980) was the pen-name of a Japanese novelist, essayist, poet and literary critic of Korean descent, active during the Shōwa period.

His father was a member of the former Korean aristocracy and a military officer serving the Joseon Dynasty, who became a Zen priest after the Japanese annexation of Korea, and subsequently committed suicide when Tachihara was five.

His Korean name was Kim Yun Kyu (金胤奎: 김윤규), but he changed his name to Nomura Shintarō (野村 震太郎) when his mother married a Japanese man.

However, he gradually shifted over the Literature Department, drawn by his interest in the novels of Yasunari Kawabata and the literary criticism of Hideo Kobayashi.

In 1958, he published Tanin no jiyū (“Other People's Freedom”) in the magazine Gunzō, followed by Takigi nō (“Firelight Noh”), Tsurugigasaki (“Cape Tsurugi”) and Urushi no hana (“Lacquer Flower”).