Searching for a shower in Haneda Airport in Japan and came across this lounge. Pay in for 1030 Yen for entry and unlimited drinks. Pay an additional 1030 Yen and you get 30 minute shower use. I dont think they keep track of the time but still be mindful you cant be in there for an hour or hours.
Great experience. There is also a nice variety of food and for weird eaters like me I was delighted to find a Burger place that was open 24/7. There are some items available for sale in the lounge as well if you wanted to get food but there is also a nice variety in the airport. You are not allowed to bring outside food into the lounge though.
www.sleepinginairports.net probably has more information if you were curious to know more specific details.
