was the first son of the Kirishitan daimyo Arima Harunobu. He was baptized as a child with the name Miguel (ミゲル). He was born in Hinoe Castle in Shimabara but was sent by his father to work beside Tokugawa Ieyasu at the age of 15. He married Konishi Yukinaga's niece Marta (マルタ); however, in order to curry favor with Ieyasu, he divorced his Christian wife and married Ieyasu's adopted daughter Kuni-hime in 1610. In 1612, he inherited his father's land valued at 40,000 koku in Shimabara when his father was executed for his role in the Okamoto Daihachi Incident. Tokugawa Ieyasu ordered a general persecution of all Christians in Japan, and Naozumi immediately gave up his Christian belief, exiled his former wife and secretly killed his two half brothers: 8-year old Francisco (フランシスコ) and 6-year