This is a book written by Yu Seong-ryong (1542-1607; pen-name: Seoae), a high-ranking official. It recorded the status of the country during the Imjin Waeran (Japanese Invasion of Korea in 1592), which started with the Japanese invasion of Korea. As a disciple of Yi Hwang (pen-name: Toegye), Yu Seong-ryong studied with Kim Seong-il and passed a state exam for recruiting high-ranking officials in 1566 (21st year of the reign of King Myeongjong). He steadily climbed the bureaucratic ladder and served as Prime Minister. He foresaw the Japanese invasion in the late 16th Century and asked the king to promote General Gwon Yul and Admiral Yi Sun-sin to important positions to make preparations to defend the country. He also recommended the production of weapons, including firearms, and the construction of defensive castle walls in major cities. He became renowned for his literary ability, calligraphy, and deep knowledge of neo-Confucianism. He was posthumously presented with the honorary title Munchung. His mortuary tablet was enshrined at Byeongsanseowon Confucian Academy, a private school in Andong. It is not known when this book was written, but he wrote it while spending his later days in his hometown years after retiring from official positions. The book contains accurate information such as the country’s pre-war relationship with Japan, the dispatch of troops by China’s Ming Dynasty to rescue Korea, the Korean Navy’s supremacy in sea battles, etc. A transcribed copy of this book was published in 7 books in 16 volumes in 1647 (25th year of the reign of King Injo) by Gyeongsang-do Governor Jo Su-ik at the request of a grandson of the writer. Another copy was published in Yamatoya, Kyoto, Japan in 1695 (21st year of the reign of King Sukjong). Its preciousness was recognized by the Korean government, and an order not to let its copy be taken to Japan was issued in 1712. The book, along with Nanjung Ilgi (War Diary) written by Admiral Yi Sun-sin, is said to be the most precious material for those studying the country’s situation during the Imjin Waeran (Japanese Invasion of Korea in 1592).