Japan's Unemployment Rate is the monthly share of unemployed people, those without work but available and seeking it, in the labour force. The labour force means all employed plus unemployed people aged 15+, counted by the Labour Force Survey. The Statistics Bureau of Japan has run it monthly since July 1947, using about 40,000 households.
It covers usual residents except foreign diplomatic and consular staff, their families, and foreign military personnel and their families. Monthly results come in the Basic Tabulation, and richer detail comes quarterly in the Detailed Tabulation. It does not count only Hello Work registrants. Discouraged non-seekers sit outside the labour force; 1 hour of paid work counts as employed.