Condition of the Japanese sword nakago
The nakago is the portion of the blade that extends below the hamachi and munemachi. On it you can find distinctive features useful for the identification of the blade, such as the yasurime (file strokes) and the mei (signature). A particular pin, mekugi, is inserted in the appropriate hole on the nakago (mekugi ana) so as to fix the latter to the handle (tsuka). A small metal collar, habaki, stops the blade inside the saya. The part of the blade inside the habaki is called the habaki moto, and the part below, where the yasurime are imprinted, is left to rust as a sign of the blade's age. The portion between habaki moto and yasurime is called sabigiwa.
Nakago ubu: Original Nakago, or identical in shape to the one in which it was conceived by the smith. Sometimes the curvature of the nakago may have been altered or slightly modified, or a new mekugi ana added to the nakago; if these changes alter the measures and sugata of the nakago only slightly, it is still identified as ubu.
Nakago suriage: shortened nakago. When a blade is shortened, this is always done on the end of the nakago, never on the kissaki. During the shortening process hamachi and munemachi are moved higher on the blade. A suriage blade usually still bears the original mei.
Nakago or suriage: greatly shortened nakago. Unlike the nakago suriage, with its slightly modified shape, the one or suriage is formed from what was originally a part of the blade. With this process, the original mei is usually completely lost, although it can sometimes be preserved in the form of orikaeshi mei or gaku mei.
Orikaeshi mei: The metal on which the mei is engraved remains attached to the blade and is then folded to the opposite side of the nakago, thus making the mei appear in reverse.
Gaku mei: The metal on which the mei is engraved is cut off in a rectangular section and then reattached to the modified nakago.
Machi okuri: to move the machi upwards. The nagasa is shortened by moving both the munemachi and the hamachi upward without shortening the nakago. The total length of the blade does not change. In some cases the nakago is shortened slightly without moving the munemachi and hamachi.
