What is Chikei in Japanese Katana terminology?

Chikei or 地景 in Japanese, refers to a type of activity that appears on the ground iron (jigane) of a Japanese sword during the tempering process. It is a linear pattern that emits a calm, black light along the forged skin (Kitae Hada). The pattern is considered to be of high quality when it forms a net-like pattern that cuts across the grain of the skin.

Chikei is similar to the gold streaks (Kinsuji) and lightning (Inazuma) that can be seen in the tempered pattern (Hamon) of the sword. These patterns are created by the same physical changes during the tempering process.

Chikei often appears when different iron materials are mixed together during the forging process. This pattern is a testament to the skill and craftsmanship of the swordsmith, and it is one of the distinctive features that set Japanese swords apart.