Originally Posted by CPH-Flyer

There is no arrival lounge. There are shower rooms, which should be free when you have a J boarding pass. Otherwise they are only 1030 yen anyway.

If you go through transit security to the departure level there is no direct and open route to immigration and arrivals, and you will need staff to escort you down. There are mixed reports on the feasibility of this, but as minimum expect to encounter some resistance to the idea. All the way up to being flatly denied.