Changes

Sori ( curvature ) does not look like suddenly fall to the ridge side at right above Nakago and the center of Sori moved upper in comparison with the previous period. We call Sori like this " Koshi-zori ". It means the sword curved at waist of a blade. The width near Kissaki is not so different from that of near Nakago, and Kissaki became little bigger. A standard length of this period is about 79cm.

Sori ( curvature ) does not look like suddenly fall to the ridge side at right above Nakago and the center of Sori moved upper in comparison with the previous period. We call Sori like this " Koshi-zori ". It means the sword curved at waist of a blade. The width near Kissaki is not so different from that of near Nakago, and Kissaki became little bigger. A standard length of this period is about 79cm.

Hamon in this period is based on Sugu-ha, straight.  

Hamon in this period is based on Sugu-ha, straight.  

The swords until this period are made in Ko-Nie. Swords made in Nioi did not

The swords until this period are made in Ko-Nie. Swords made in Nioi did not exist yet.

exist yet.

* Middle Kamakura (1232 - 1287) :

* Middle Kamakura (1232 - 1287) :