Konghai is one of the greatest calligraphers in Japan. Feng Xin Tie is the clearest three letters of Konghai, and also the most important calligraphy masterpiece after Konghai returned to China. It is said that there are five original letters, each of which is independent. In addition to the existing three links, the other two are dedicated to Guan Bai Chen Feng, and one is stolen and lost.