Micello maps have a default language, which is generally English. If no language is specified or the specified language can't be found, the default is loaded.

Language is specified during map initialization:

micello.maps.init (apikey, mapInit);
function  mapInit() {
    var mapControl = new micello.maps.MapControl('mapElement');
    micello.maps.request.lang = ''; // 'ja' for japanese, 'en' for english
    var mapDataObject = mapControl.getMapData();

This community, #1709 - Lalaport Toyosu, has both English and Japanese data. Try entering the values 'en' or 'ja' and see how it affects the map language.

List of language supported and language codes are available here.