Before that
Reported by Yahoo! Singapore, Dec. 24th, 2001: South Koreans welcome Japanese emperor's remark on his roots South Korean political parties and newspapers welcomed Japanese Emperor Akihito's surprise remarks that his roots may partly be traced to the Korean peninsula. Akihito's reference...
according to wikipedia
Kammu was the son of Emperor Kōnin. According to the Shoku Nihongi, (続日本紀), Emperor Kammu's mother Yamato no Niigasa, later Takano no Niigasa, was a descendant of King Muryeong of Baekje, Korea. Kammu was born before his father ascended to the throne.
After his father Kōnin became emperor, Kammu's half-brother was appointed to the rank of the crown prince. Later Kammu was named to succeed father instead of his brother.
私自身としては、桓武（かんむ）天皇の生母が百済の武寧王（ぶねいおう）の子孫であると続日本紀（しょくにほんぎ）に記されていることに、韓国とのゆかりを感じています」と語られました。
around AC400 king of Baekje, 蓋鹵王 sent his daughter(池津媛) to japan as a hostage
because Baekje needs Japan to defend her against Koguryo.
1) afetr that ,she was killed in japan ...the story was so sad.....
2)軍君 , brother of 蓋鹵王, was sent to japan instead of her
3)son of 軍君, 武寧王 was born in japan as #25 king of Baekje, so,he was called Shima島王
4)after that, the son of 武寧王 was sent to japan as a hostage..
5)his son was sent to Japan. after him, His decendants settled in japan
6) 〃 became a japanese
7)〃
8)〃
9)〃low class government official, His daughter married the emperor's family.
then he was given the name of "Takano"
10)高野(takano)新笠 AC733,she became #49 Emperor 光仁 's concubine.
AC773 her son, Kanmu became a prince and 781 became #50 emperor
桓武天皇は白壁王の第一皇子として天平9年(737年)に産まれた。初名は山部王。父の白壁王の即位後も母の高野新笠が下級貴族に属していたため、立太子は望まれておらず、当初は官僚としての出世を目指しており、大学頭などを歴任していた。しかし、藤原氏などを巻き込んだ政争によって異母弟である前皇太子他戸親王とその母であった皇后井上内親王が突如廃されて宝亀4年（773年）に立太子。天応元年(781年)、4月15日､即位。
I think it was good..
blood or race are meaningless for emperor.
emperor in male line is only needed .....