This fist can be tightened in two ways. All fingers except the middle finger can be closed as in the tsuki, with the tips of the ring and index fingers touching to prevent the middle finger from slipping into the palm.
In the alternative, the index finger is extended toward the wrist, while the thumb presses the other fingers together.
The Nakadaka ippon ken uses the second knuckle of the middle finger to hit small vital points that cannot be reached with other techniques due to the larger target areas.
This technique can also be used for defense (at the same time it is intended as an attack on the attacking hand - an example of this is the kata Chinte).
