People who returned to big cities began their first day of work Monday after spending the New Year's holidays overseas or at their family homes.

Due to the calendar, this year's holidays were relatively short, and many companies as well as public organizations started operations Monday.

In the political arena, the Diet was scheduled to open an ordinary session Monday earlier than usual, with political parties weighing on the July Upper House election.

To get back to work in time, people across the country rushed home Sunday, which led to record-level congestion on trains, airlines and road traffic.

Most seats on shinkansen bullet trains bound for Tokyo were taken, with the occupancy rate for nonreserved seating hitting 160 percent on some trains leaving Fukuoka for the capital, Japan Railway companies said.