The “Calendrical Book of the Gyeongja Year (1600) with Memoranda by Ryu Seong-ryong,” a metal-type printed book published in 1599, has been unveiled to the public after being acquired from Japan, the Cultural Heritage Administration (CHA) said Thursday. As a high-ranking official and Confucian scholar, Ryu was the equivalent of the prime minister during the reign of King Seonjo (1567-1608) during the Joseon Kingdom, and he was a longtime friend of Admiral Yi Sun-sin (1545-1598).