Japan residential property prices: undervalued?

CEIC and UBS have compiled data comparing changes in residential property prices across Asia since before the global financial crisis. In comparison to markets such as Hong Kong (up over 140% since 2006), Singapore (+80%), and Korea (+40%), Japan appears relatively undervalued (down 20% nationwide since 2006).

Of course, national figures only tell a partial story. In the Tokyo area apartment prices have been increasing at a steady clip for the past few years, and in 2015 the country saw land prices rise nationally for the first time in eight years.
Sources:

CEIC & UBS Calculation