This visualization displays a choropleth map of Japan’s administrative regions, with each prefecture filled in a uniform red color and separated by white borders. The map uses an equirectangular-like Mercator projection via `d3.geoMercator` and renders geographic features with `d3.geoPath`. The code loads TopoJSON data for both states and districts, then applies `d3.scaleOrdinal` with a category color scheme, though only the state layer is drawn. Interactive zoom and pan are supported through D3’s `zoom` behavior, which transforms the SVG group containing the map paths.