By the way, was there a teacher of Yin and Yang during the Warring States Period?

Yes, the profession of Yin and Yang teacher gradually disappeared after the Meiji Restoration.

Master of Yin and Yang is a wizard who has mastered Yin and Yang, knows how to look at the stars and face people, also knows the direction, knows the disaster, recites spells and performs illusion.

Yin and Yang teachers originated in China and are widely popular in Japan. Its unique spell "Yin and Yang Dao" is a part of Japanese Shinto. People are well aware that invisible forces, such as fate, soul and ghost, have the ability to dominate these things. Their activities are sacrificial rites, divination, calendar revision and official duties (auxiliary politics), and the representative figures are Abe Seiming, Lu Wudao Man, Guan Le monk Zheng.

During the Warring States Period in Japan, imperial power declined, the samurai class ruled the world, and the division of Yin and Yang gradually disappeared from the historical stage. However, most of the military advisers around Daming are Yin and Yang divisions. Celebrities in the Warring States paid great attention to divination, and the military fan in the hands of military commanders was a kind of spell. Both sides of the military fan are painted with a day and a month. In case of a fierce day when you have to go out, the moon surface of the army fan will appear during the day, so that day and night will be reversed, thus turning the fierce day into an auspicious day. Although the rank of Yin-Yang division is not high, it is mostly relied on by powerful ministers and nobles, and its position is far above that of ordinary officials and warriors.