But before you jump on a train, think twice. In Japan NOBODY speaks or understands English. So, it might be better to stay away, when you travel alone and also don't spreak or understand the local language.

At night it seems the Tokyo Narita airports closes. And they even shut down the lights. If you try sleeping overnight at the airport, you will probably end up in a dedicated area by local police, where they might ask you for your passport once every hour all night long (and wake you every time over and over again). The good news: there seem to be several hotels near the Tokyo Narita airport terminals.