Proportion of empty houses in Japan, taken from this page by @yasufumisaito but adapted to use the d3-composite-projections.
The data is originally from the Statistics Bureau at Ministry of Internal Affairs and Communications.
Modified http://d3js.org/d3.v3.min.js to a secure url
Modified http://d3js.org/topojson.v1.min.js to a secure url
Updated missing url https://cdnjs.cloudflare.com/ajax/libs/d3-composite-projections/0.3.5/conicEquidistantJapan.min.js to https://cdnjs.cloudflare.com/ajax/libs/d3-composite-projections/0.3.5/conicequidistantjapan.min.js
https://d3js.org/d3.v3.min.js
https://d3js.org/topojson.v1.min.js
https://cdnjs.cloudflare.com/ajax/libs/d3-legend/1.7.0/d3-legend.min.js
https://cdnjs.cloudflare.com/ajax/libs/d3-composite-projections/0.3.5/conicEquidistantJapan.min.js