April 30th, 2019 is the last day of the Heisei Period!
The Heisei Period started in 1989 and will end today, shortly after entering its 31st year.
This is a special occasion for everyone, because Periods end when the emperor dies. However, the Heisei Period Emperor had shown interest in stepping down from the throne since years ago, leading to a change in constitution and new set of laws, leading up to today. Therefore, this is the only time we know that a Period is ending.
The Japanese TV shows are going crazy with the idea, including shows that look back at the 30 years of the Heisei Period, do things with the title of "Last ___ of Heisei", and shows that are doing a 25 hour live stream into the new period.