Enkiri

Enkiri is a technique created by Shinsui that allows him to channel his concentrated fire-infused chakra through his blade. Intense quasi-flames are concentrated on the edge of his sword, although, they are not made evident enough to be detected by the naked eye; the only sign of this happening is a feint line of smoke appearing on the edge of the blade, this greatly increases the lethality and destructive power of Yagen. Since the fire-infused chakra envelops the sword, it naturally extends the total reach of the blade by a few inches due to the amount of kinetic energy it generates, thus creating an invisible "heat" extension which adds about 3-inches of additional range to Shunsui's sword strikes and thrusts.

Trivia

 * It is also possible that the "kiri" part of the name is a reference to Kiriai (切り合い, Kiritai) which means "crossing swords" or "sword fighting".
 * This technique has also been called "Blade of Single Ember (単燠の刃, Hitoe-oki no Yaiba)".