On the back side, a hallmark consisting of four characters is carved and the hallmark is one of the following three combinations: '次・七・源・九' (nami, seven, gen, nine), '坂・七・源・九' (saka, seven, gen, nine), '弥・七・源・九' (ya, seven, gen, nine).
裏面に「次・七・源・九」、「坂・七・源・九」、「弥・七・源・九」のいずれかの極印が打たれている。