A sword.
There is a dragon pattern printed on the back of the sword, who will be the emperor between heaven and earth.
A knife.
The back of the sword prints flowing clouds, and I can come and go freely.
A fan.
The calligraphy and painting on the back of the fan have become a guest in the dust and flowers.
A needle.
With gold characters in seal on the back of the needle, he traveled alone in the rivers and lakes to fight against rampant evil.