I touched on tenouchi in an early post on holding the shinai and in my report on Chiba sensei’s first UK seminar. I make no excuses for posting about it again, because it is an important aspect of kendo and in many cases, the final piece of the puzzle that decides whether or not a technique results in ippon.
Tenouchi translates simply as “the inside of the hand” and in kendo means the squeezing action of both hands at the point of striking. If you squeeze too hard or too early, the point of the shinai will not extend forward sufficiently to strike the target correctly and crisply. In some kendojo people were, and maybe still are, taught to wring the shinai between both hands at the point of cutting. Unfortunately this has the effect of causing the point of the shinai to rise on impact, so it actually defeats the purpose of using it as an aid to finish the cut correctly.
Like every other component of kendo, tenouchi should be relaxed and natural. Rather than create an artificial action at the end of your cutting swing, you should start the movement holding the shinai correctly. That is with the end of the tsuka fitting into the heel of your left hand and the little finger and ring finger applying slight pressure with the middle , index finger and thumb barely making contact. For the right hand the grip is the same, but if anything lighter and the knuckle of the forefinger should lightly brush the tsuba. If this is uncomfortable, chances are your tsuka is too long. I cannot overemphasise that your grip should be light. If someone tries to pull your shinai forward out of your hand, it should slide forward without protest or friction. A further key point is that your wrists should turn in slightly, so that the centre of the V formed by thumb and forefinger of each hand should be at a 90 degree angle to the ground.
Holding the shinai in this way, you should aim to cut through the men to chin level and kote through the thickness of the wrist and squeeze lightly with the little and index fingers after the point of impact. You should not change your grip at any stage of the cut.