He was also known by Ufu Aragusuku (大新城), and his Chinese style name, Mō Ryūgin (毛 龍唫).
According to legend, Aragusuku was a love child of King Shō Shin.
The king ordered three ministers, Aragusuku Anki, Kunigami Keimei (国頭 景明, also known by Wa Imi 和 為美) and Gusukuma Shūshin (城間 秀信, also known by Katsu Kashō 葛 可昌), to assist the Crown Prince Shō Gen.
They said that Shō Gen was too sickly to succeed the throne, and many ministers supported them.
He stood in the audience hall, with a naginata in his hand, and said that Shō Gen was the eldest son of the Queen Umimajingani Aji-ganashi, so he should be the new king because of the primogeniture.