Features of research misconduct (RM) in Japan were as follows: (1) a half of RM was plagiarism; (2) the ratio of the mentors - professors, associate professors, primary investigators and so on - who made RM was more than 50 percent of whole RM; (3) the punishments for RM were irregular and had a wide range from no-punishment to the dismissal; and (4) it took about 4 years on average to find out about a half of RM. In order to improve research ethics in Japan, the top priorities are the enlightenment of the mentors and also the preventing plagiarism.