was a local ruler of

Okinawa Island , officially , is the largest of the Okinawa Islands and the Ryukyu Islands, Ryukyu (''Nansei'') Islands of Japan in the Kyushu region. It is the smallest and least populated of the five Japanese archipelago, main islands of Japan. The island is ...

, who was given the title of King of Sannan. He first contacted the Chinese emperor in 1403, claiming himself to be a younger brother or cousin of Shōsatto, the late King of Sannan, who reportedly had no son. Ōōso was given the title in the next year. His last contact was of 1413. In 1415, Taromai, who styled himself Crown Prince, reported Ōōso's death. He claimed that Ōōso was killed by his elder brother Tabuchi, who had in turn been killed by local chiefs, in favor of Crown Prince Taromai. His real name is unknown. The name ''Ōōso'' is enigmatic and highly un-Okinawan. A desperate attempt of decipherment relates it to Yaese (八重瀬), a fortress in southern Okinawa. Historian Ikuta Shigeru speculates that the King of Sannan was a puppet of the King of Chūzan from the very beginning. According to his theory, Ōōso reported to the Chinese emperor that King Shōsatto had no son because Shōsatto and his offsprings actually defected to Korea in 1398. Before the recognition by the Chinese emperor, Ōōso was appointed as King of Sannan by the King of Chūzan. Similarly, historian Wada Hisanori suspects that Ōōso was not a younger brother or cousin of King Shōsatto and that it was a made-up story to eliminate Chinese suspicion. Based on the assumption that by that time,

Shō Hashi Shō Hashi (1372–1439) was a king of Chūzan, one of Sanzan period, three tributary states to China on the western Pacific island of Okinawa Island, Okinawa. He is traditionally described as the unifier of Okinawa and the founder of the Ryuky ...

, the unifier of Okinawa Island, had already kept Sannan under his control, Wada claims that Ōōso was either a pseudonym of Shō Hashi or his puppet ruler. The ''

Chūzan Seikan , compiled in 1650 by Shō Shōken, is the first official history of the Ryūkyū Kingdom. In six scrolls, the main text occupies five and an accompanying summary the sixth. Unlike later official histories such as ''Chūzan Seifu'' and '' Kyūy� ...

'' (1650) and

Sai Taku , also known by his Japanese-style name , was a Ryukyuan aristocrat and bureaucrat in the royal government of the Ryūkyū Kingdom. Sai Taku was born in Kumemura on January 4, 1645. He descended from Cai Xiang, a famous polymath of the Song dyna ...

's edition of the ''

Chūzan Seifu was an official history of the Ryūkyū Kingdom compiled between 1697 and 1701 by a group of scholar-officials led by Sai Taku. It was a continuation of the '' Chūzan Seikan''. It is composed of 19 volumes, one of which is devoted to correspon ...

'' (1701) made no mention of Ōōso, suggesting that the name of Ōōso was not transmitted among the Okinawan society.

Sai On (1682–1762), or Cai Wen in Chinese, also known as , was a scholar-bureaucrat official of the Ryūkyū Kingdom, serving as regent, instructor, and advisor to King Shō Kei. He is renowned for the many reforms he initiated and oversaw, and is amo ...

's edition of the ''Chūzan Seifu'' (1725) drastically rewrote history. Having access to Chinese diplomatic records, he added the records of tributary missions sent under the name of Ōōso. Sai On dated Ōōso's death to 1414.

Notes

{{authority control Kings of Sannan