There is a prayer room in Haneda Airport.
http://www.haneda-airport.jp/inter/en/premises/service/others.html#pray
It is in the area in front of the departure area of the departure floor, near the new check-in counter “L.”
This place is provided with a water place for Wudu, and may be freely used regardless of religion, but eating, smoking, and other actions not suitable for the prayer room are prohibited. When using the prayer room, it is necessary to call an attendant by an intercom placed beside the door. It is available 24-hours and is free to use.
Airports in Japan will be working to make preparations for accepting Muslim customers.
