CultureInfo ci = new CultureInfo("ja-JP");
Thread.CurrentThread.CurrentCulture = ci;
Thread.CurrentThread.CurrentUICulture = ci;
ci.DateTimeFormat.Calendar = new JapaneseCalendar();
this.xamDateTimeEditor1.FormatProvider = ci;
this.xamDateTimeEditor1.Language =
XmlLanguage.GetLanguage(ci.IetfLanguageTag);