Final answer:
Matthew Perry, a Naval officer, opened Japan to Western trade and diplomacy in 1854 by signing the Treaty of Kanagawa.
Step-by-step explanation:
In 1854, the Naval officer who opened Japan to Western trade and diplomacy was Matthew Perry. He sailed into Edo (Tokyo) Harbor in 1853 with four ships and an offer from the U.S. government to establish relations with Japan. Perry threatened military intervention if Japan did not agree, leading to the signing of the Treaty of Kanagawa in 1854, which opened Japanese ports to the West.