A Udon kiri (うどん切) or Soba kiri (そば切 or 蕎麦切り包丁) is a specialized knife used in the Japanese kitchen to make soba and udon noodles. The knife is also sometimes called Menkiri bocho (麺切り包丁). To make soba or udon the dough is flattened and folded, and then cut with the menkiri bocho to produce long rectangular noodles. For this purpose the menkiri bocho has a straight and long cutting edge to cut the noodles straight to the board. The knife is usually heavy to aid in the cutting of the noodles, usually with a slight forward motion.
See also Japanese kitchen knives and the list of Japanese cooking utensils.