The red-hot block is struck and elongated using a Tsuchi (hammer), and folded back into the middle of its length, which is called a 'folding method of forging' and it is done repeatedly. In fact, the word 'Muko-zuchi,' describes the method by which Tosho (Yokoza, master) and his disciple (Sente, helper) alternately strike the body of the blade with a Tsuchi, and this has become the root of the word 'Aizuchi wo utsu (chiming in).' In this step, folding is done about five or six times.