Jacobo Kyushei Tomonaga was a 17th-century Japanese Dominican priest born in the Kyushu region. After training with the Jesuits and serving as a catechist, he joined the Dominican Order and was ordained in 1626. He spent time as a missionary in Formosa before returning to Japan during a period of intense religious persecution. He eventually faced martyrdom in Nagasaki, where he died following imprisonment and torture after being discovered by authorities.