For about a week from this weekend, we have holiday season in Japan as there are several legal holidays within a week or so.
April 29th, which is date of birth of the Showa Emperor Hirohito, is the SHOWA DAY.
April 30th is a legal holiday as the SHOWA DAY in this year is Sunday. It's due to National Holidays Act.
May 3rd is CONSTITUTION DAY.
May 4th is DAY FOR GREENERY.
May 5th is CHILDREN'S DAY.
Today, April 28th is not a national holiday, but the most meaningful day for the last 60 years to the Japanese people. On this day in 1952, San Francisco Peace Treaty took effect. On the very same day, Security Treaty Between Japan and the U.S. also took effect.
The Japanese people lost all right, title and claim to Chishima(Kurile) Islands and South Karahuto(Sakhalin), abiding by Article 2 (c) of San Francisco Peace Treaty.
This means that the Japanese people had all right, title and claim to Chishima Islands and South Karahuto up to April 27th, 1952.
In the high summer of 1945, Soviet Union(present-day Russia) invaded a part of Japan's territory, including Chishima Islands and South Karahuto. In the modern era, invaders never acquire land which they invade.
However long Russia occupy land they invaded, they never acquire it. That's the basic rule of modern era obeyed by modern nations.