The fact is that Shibuya is youthful, lively and relatively safe. It's thousands of restaurants and bars are filled with party people night after night.
Shibuya's restaurants and bars start to get busy around 7 pm (any night of the week). They stay busy until last train. Tokyo people generally stay out until their last train. Depending on the train line and distance this is usually 11:30 P.M. to 12:30 A.M.
Those who stay past last train usually stay until first train (5 to 6 A.M.). The late night crowd go to bars, clubs and karaoke.
Just as the late night crowd stagger out of their bars and karaoke for their first train: Shibuya is just heating up. The morning commute is in full swing. Every day, 2.4 million people pass through Shibuya station.
By 9 A.M. Shibuya is starting to fill with shoppers. It's one of the busiest shopping districts in Japan.
As the shoppers head home in the evening the cycle begins again.