Conversation so far:
when does the work week start and end
The workweek can start on any day and at any time. It does not have to follow a calendar week. The workweek must include seven consecutive days.
when did the romas begin using the seven-day week
The ancient Romans traditionally used the eight-day nundinum but, after the Julian calendar had come into effect in 45 BC, the seven-day week came into increasing use.
When did Asia begin to use a seven day week
The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century in the Jin Dynasty.

Question: What about Japan
Self-contained rewrite: When did Japan begin to use a seven day week