Main cutting portion of blade (first six inches from kissaki).

The blade area can be divided up into three main zones.

The closest zone to the tsuba is, what most people would expect it to be, the area for defending oneself (it is the zone which is used in the initial contact of the seiteigata Ukenagashi). This zone is called the "Bō" (no relation to the Japanese staff) and is referred to also as the "tsubamoto" (origin or zone of the tsuba).

The middle zone is called "Sei" meaning control i.e. this is the region that controls the enemy's sword during a deflection or similar movement. It is also referred to as the "nakahodo" (meaning approximate centre).

The zone closest to the end is called "Satsu" (or "Setsu") meaning the killing region. This region is also known as the monouchi.