Is there free boiled water at the Japanese airport?

No. Because Japanese people don't have the habit of drinking boiled water. They all like to drink mineral water, even in cold winter. When eating in Japanese restaurants, the first thing is a glass of cold water, which is very popular among the elderly and children. This is also the difference in living habits of a country.

There is no boiled water at the airport. There are many vending machines selling hot coffee, cocoa and other drinks. There is hot tea, but there is no hot water.