Episode 5: Investigation! The Mystery of the Goguryeo-Sui Wars. Even before the founding of the Sui kingdom, Goguryeo was constantly under attack from China. Those battles involved armies of tens of thousands of troops. In 598, the Sui Dynasty in China invaded Goguryeo with an army of more than 300,000 troops, but they were completely defeated. How could this have happened? Episode 6: Does the Japanese Imperial Family Have Baekje Blood? The mother of Emperor Kanmu of Japan was a descendant of Baekje's King Muryeong. Japan's imperial family has acknowledged ties between ancient Japan and Korea, but only in terms of cultural exchanges. Discussion of anything as sensitive as the imperial family's lineage has been outright forbidden in Japan. That is because the family's lineage contains a secret about the relations between the two countries in ancient times. To begin, we must find out who the mother of Emperor Kanmu was.