It is a national holiday called Showa no hi (昭和の日), Day of Showa. It used to be Emperor Showa's Birthday, and became Midori no hi (みどりの日), Greenery Day, and now Show wa no hi.
From April 29 the Golden Week starts in Japan. This year if you take May 1 and 2 off you get 8 days off. Many people must travel abroad.
I am now in Santorini, Greece and today I enjoyed the sunset cruise.