According to your major, find official website from various Japanese national, public and private universities, find the name, email address and mailing address of the professor in the research office of the relevant major, and submit your resume. It is best to carefully study the papers published in our laboratory, find out a research direction that interests you, look up information on the Internet and in the library, and simply write a research outline. This is an important content that can impress professors to interview you. In short, I wish you good luck, and "がんばってくだ".