There is always a laundry where there is a public bath, so the easiest way to get to a laundromat is to follow signs to a public bath.
Public baths are places where one can take a hot bath as well as shower for a charge.
The baths are separated into a male and female sections. Everyone of a single sex goes into the same room and there are not separate compartments for each customer. Of course, no clothes or bathing suits are allowed inside the bath and there are locker rooms outside the bath where customers can leave their clothes and belongings. Public baths date back to long time in Japanese tradition and there is no embarassment among bathers about nudity, which can often be an unusual concept for the non-Japanese. Public baths are kept very clean and one must always take a shower before stepping into the hot bath tub.