Was thinking about this today as before Perry arrived to represent the United States, Japan had voluntarily closed itself off from the world for centuries (except the Dutch). Because the country was essentially isolated from the rest of the planet, were there any English speakers/readers left in the country? Conversely, was there enough a Japanese-speaking population outside of Japan that Perry was able to bring along a translator? If not, how did he address the communication difficulties when he went on his mission to Japan?
Perry brought translators with him, and the Japanese knew Dutch. The main languages of communication were Dutch and to a lesser extent Chinese. See here by /u/diana_mn
You got a good overview of the issue linked below, but to answer your question about English speakers in the country, yes, there were. A representative of the Shogunate named Moriyama Einosuke at the negotiations could speak English fairly well. Here's an excerpt from Williams' diary:
Friday, March 3rd.—Yezaimon ate and drank so much at Buchanan's dinner he was unable to come off to the ship as requested last night. A new and superior interpreter came with Saboroske, named Moriyama Yenoske, who had recently returned from Nagasaki, whence he arrived in twenty-five days and hurried on at that. He speaks English well enough to render any other interpreter unnecessary, and thus will assist our intercourse greatly. He inquired for the captain and officers of the "Preble," and asked if Ronald McDonald was well, or if we knew him. He examined the machinery and at last sat down at dinner in the ward room, giving us all a good impression of his education and breeding.
Ronald McDonald (actually spelled Ranald MacDonald) was a well educated, half Scottish/half Native American man from Oregon who became fascinated with the idea of Japan and paid a whaling ship captain to purposefully "shipwreck" him there in a small rowboat. He was arrested and brought on the long journey from Hokkaido to Nagasaki, where he was kept under house arrest until he could be repatriated. During this time, he managed to teach English to some of his "captors" through the bars of his prison, and one of the most gifted of his students was Moriyama, who would later become a crucial part of the negotiations with Commodore Perry.