The chokuto (pronounced "choh-koo-tow") is a straight sword. Prior to the advent of clay technology that allowed a differentially hardened blade (harder edge and softer body thus creating a temper line in the shape of the clay application) the Japanese swords of the time were straight, since the differential heat treatment using clay would cause the blade to curve once it emerged from the quenching waters.

In later periods, chokuto could be made even with clay to achieve a hardened edge during the final heat treatment and quenching. Since this would normally cause a blade to curve, the process of making swords this way yet keeping them straight was considered to be a much more skilled (and possibly more costly) process.

The Hollywood "Ninja-to" was a straight blade but not the classical chokuto, since ninja-to were meant to be discardable. However, consider that some ninja were Samurai or Ronin, it made more logical sense to have a regular curved sword to eliminate any chance at a ninja being identified by his straight short blade.

ILLUSTRATION BY ADRIAN KO