Because there has never been a shochoku (imperial edict) for the transfer of the national capital to Tokyo, there has been no change to the fact that Kyoto is officially the capital of Japan even now while the imperial system continues.
東京遷都の詔勅が発布されていない故、天皇制が存続する現在もなお京都が、公式に日本の首都である事実に変わりは無い。