According to the Ministry of Internal Affairs and Communications, as of 2013, 34.6 percent of all Japanese households owned washing machines with some sort of drying function. For the most part, these were drum-type (i.e., front-loading) appliances that both washed and dried, and thus the statistic did not take into account households with separate stand-alone clothes dryers. The ministry estimates that, counting these independent dryers, about half the country has the means to dry clothes by machine at home.
However, a different survey conducted by Tokyo Gas in 2013 concluded that 60 percent of Japanese households that own clothes dryers in any form never use them, the main reason being that people believe open-air drying is better, since sunlight supposedly acts as a kind of disinfectant. Seventy percent of all respondents, regardless of whether or not they have dryers, say they prefer drying clothes in the sun. Some also say they prefer the way sun-dried fabrics smell.
So if the majority of people who own dryers and washing machines with drying functions don't use them, why do they buy them in the first place? The answer is not forthcoming in any of these surveys, but the sun is free, and drying clothes at home mechanically is very expensive.