I just read Charles Boxer's book "The Christian Century in Japan" and I wanted to write a paper about how the jesuits' power in japan was heavily tied with its control of the Macao-Nagasaki trade. I just wanted to know if there are additional information that could help my paper which are not found in the book or if there could have been inconsistencies.
I'm not sure exactly what you are asking, but if I were to read your question literally, the answer is that Portuguese presence in Japan is due to trade, and further for a long time they were the only Christian power in direct contact with Japan. Spain was excluded due to strategic agreements between them and the Portuguese, and other European powers lagged behind.
Portuguese traders reached Japan in 1543. The Dutch only came in the early 1609, the English in 1613. The Spanish could only trade with Japanese ships visiting Manila.