What days of the GW, apart from sundays, are official holidays?
There has been a change from 2007 in offocial holidays over the Golden Week.
April 29 - Showa Day (until 2006 Greenery Day)
May 3 - Constitution Day
May 4 - Greenery Day (until 2006 National Holiday if not a Sunday or Monday)
May 5 - Children's Day
If any of these days falls on a Sunday, the following Monday becomes a holiday instead. So this year, Showa Day will be kept on April 30.
According to Tsukiji Market Calendar 2007, the market is closed on April 29, 30, May 3, 5 and 6, but opening specially on Saturday May 4th.
Closures over GW differ wildly and you need to check with individual places to be sure. Generally, larger stores stay open throughout, as do entertainment and leisure facilities. Closed are offices, banks and post offices, and there will be very restricted operating hours for ATMs. Post Office ATMs will be closed from May 3-5 for software update.
