The "Sleeping space of eels"
Machiya have a very distinct form in that they are very long compared to the width of their front. This is due to two main factors: the plots that were assigned to commoners were not very large and longer than wide in the first place. With several houses sharing the width of a plot, the space a building occupied was maximised by making it longer. The second reason is that, until approximately 150 years ago, taxes were calculated based on the width of a building's frontage. The owners of machiya circumvented high taxes by making the houses' façades comparatively small and elongating them towards the back of their respective plot. This evoked the nickname "sleeping space of the eels" (unagi no nedoko). A typical layout of a machiya looks like this:
Directly adjacent to the street is the mise no ma, the space where the business is conducted or the products are fabricated. The earthen or concrete floor next to it is called the miseniwa, and it is here that customers will come in from the outside. Separated from it by a door or a noren is the hashiriniwa, where the hearth and well are (could be) found. Hashiriniwa and miseniwa together are called the tōriniwa, which stretches from the front entrance all the way through to the back of the house.
From the hashiriniwa, one can access the daidoko and the zashiki. In big machiya, there is often a formal entrance, called genkan. During Japan's feudal ages, this entrance was only used by the household head and the heir to the household as well as important guests who were invited to the zashiki by the head. Other family members would not use it except on very important holidays.
The daidoko is the place where most of the living takes place. It is here that the family sits together for dinner or joint activities. In other words, it is a living-dining room. Also, it is not to be mistaken for the kitchen, because in modern Japanese daidokoro (台所) is the word for kitchen. To prevent misunderstandings, most Japanese publications transcribe the living-dining room in Katakana symbols as ダイドコ.
Next to it is, as mentioned before, the genkan or the zashiki. This is the most important and usually also largest room in the house and has a very formal connotation to it. In the zashiki there is also the alcove, called toko no ma. Here, picture scrolls are hung from the wall, some flowers are tastefully arranged, and family valuables are put on display. From the zashiki, the visitor can enjoy looking at the garden outside. Many machiya have at least one such garden, bigger ones even two. They do not only function as a refreshing view to the eye, but also as a natural air conditioning unit.
The layout presented here is a very general one, showing the most common parts of a machiya. There may be more to some houses, such as a storehouse with thick earthen walls (kura) on the other side of the garden, or even more rooms.