[2][3] In (CE 1592), as the eldest son of Ōmura Kizen, a daimyo (later the first lord of the Omura domain) under the Toyotomi regime, Born in Miki[clarification needed].
From an early age, he conducted joint politics with his father, and in 1607, with the permission of Tokugawa Ieyasu, he entered into the Gogo in order to secure financial resources and strengthen the power of the feudal lord.
In November (CE 1614), he participated in the Osaka Winter Siege on the Tokugawa side, and served as a guard at Nagasaki.
In September 1614, before the invasion of Osaka, he was ordered by the shogunate to destroy the church in Nagasaki along with the neighboring clans of Nabeshima, Terasawa, Arima, and Matsuura.
Around (CE 1617), Alfonso Navarrete of the Dominican Order and João Batista Machado of the Jesuit, had four foreigners missionary beheaded: Pedro Asumpción of the Franciscans and Hernando de Araya of the Augustinians.