The main and most complicate element of a Japanese armour is the helmet, named kabuto. Although there are common elements between the various helmets, throughout the centuries they were produced in different shapes and models, according to the various schools.
Kabuto are very often decorated with applied elements (datemono): the most common position is certainly the front (maedate), but there are also ornaments on the side (wakidate), on the rear (ushirodate), and on top (zutate). The most common maedate are those with two large stylized metal horns (kuwagata).Kabuto can be classified by their construction techniques as follows:
1. Lamellar structure helmets
These are japanese helmets with vertical plates (up to 120 in some cases) posed one side by side the other, connected on the top of the helmet where we have an opening (tehen), surrounded by a decorative ring (tehen no kanamono). The two main models of this group are:
- the koboshi kabuto has each plate secured to the next one by rivets (about 1,800 rivets in a 62 plates helmet), often with decreasing size near the top of the bachi and accurately aligned.
- the suji bachi kabuto has the same construction as above, but the rivets are almost invisible because they are clinched. In this way the most noticeable part of the helmet becomes are the folded edges of the plates (suji). Brass cover (fukurin) is sometime present on the plates.
2. Plate kabuto
These are made using a small number of plates. Conceived to be built economically and quickly, there are anyway more complex variations suitable for high rank samurai. The two main models of this group are:
- the zunari-bachi-kabuto ('head shaped helm') is constructed joining three plates without edges or rivets, so that they appear smooth.
- the momonari-kabuto ('peached-shape helm') derived from western helmets. It is generally composed by two plates tied at the center. However, there are more fancy variants, made with lamellar structure.
3. Extraordinary helmets (kawari kabuto)
The kawari kabuto category counts actually many different types of helmets that avoid the traditional classifications or have eccentric shapes and ornaments. Even if there are names that classify different forms, usually inspired by sacred objects or elements of nature, each helmet is virtually unique. It's possible to find some major categories of kawari kabuto that allow us to better understand this so extensive and often abused definition.
- Harikake kabuto: the most spectacular helmets are generally those with a superstructure made of papier mache, wood or leather which completely covers the metal bowl. The use of light materials made it possible to create different and fanciful shapes, almost without limits.
- Tetsubari kabuto: this category includes helmets made of iron in unusual shapes. Examples of this kind are the okitenugui helmets of the Saika School and those which are inspired by other headgear.
- Uchidashi kabuto: the embossing (uchidashi) gives unusual and very attractive shapes to helmets built only of one or two plates. this is an extremely complex manufacture, which however, weakens iron reducing its protective power; for this reason the uchidashi kabuto are more common during the Edo period.
- Nanban kabuto: these are kabuto whose design derives from the European helmets imported by the Portuguese during the sixteenth century. They are frequently inlaid with gold and silver.