Ōkimi in Japanese reading is created by adding the prefix ō or oho which indicates greatness and particular nobleness, to the title "kimi" (lord), which indicates a master or nobleman.
[4] The kanji title "王" (Ō, Wang) originally designated a Master of Chūgen (中原, Zhongyuan) in Inner China.
In the Zhou dynasty period, 王 (Wang) was the title of the sole Son of Heaven who rules the Tianxia.
When China entered into the Warring States period, the monarchs of the great nations among the states of North China who were originally subjects of the Zhou King, but achieved territorial statehood, called themselves sole Wang of the Tianxia in place of the Zhou King.
[5] The word Wakoku ō (King of Wa) appears in the article dated to the first year of Eisho (107 AD), in the record of Emperor An in the Book of the Later Han.
[7] The kanji letters of the title 大王 (ōkimi, great king) was first appeared in the inscription of the iron sword unearthed from Inariyama kofun, Saitama prefecture.
When Toshio Kishi and other researchers tried to decipher this inscription, they re-examined the reading of the script on the sword from the Eta Funayama kofun.
There is the inscription 「癸未年八月日十 大王年 男弟王 在意紫沙加宮時 斯麻 念長寿 遣開中費直穢人今州利二人等取白上同二百旱 作此鏡」 (according to Toshio Fukuyama) [10] on the Suda Hachiman Shrine Mirror (Portrait of person Mirror), owned by Suda Hachiman Shrine, Wakayama prefecture, in which the words 大王 and 男弟王 appear.
From this inscription, in the year Mizunoto Hitsuji (癸未, Kibi) [11] when the mirror was made, the title Daiō is supposed to have been used.