Japan officially known as the Empire of Japan was an island country in northeastern Asia. Its capital city was Tokyo.
Tony Delgatto's son Wil moved there and started a family without including Tony. Some unknown area is shown briefly when Tony calls his family, then an earthquake hits the unknown area which killed his family and the telephone connection exploded and ceased. It's assumed that his family was killed after their house was destroyed.
It was reported on the BBC which is watched by Genesis' crew, Tony and Harry in the Genesis ship that Tokyo was hit by a massive earthquake and much of the country was flooded by tsunamis.
In the aftermath of the 2012 apocalypse, Japan was destroyed and rendered uninhabitable with most of its population being killed. The only known survivor of Japan is its Prime Minister.