[2] The hiragana used, however, is a traditional orthography which associates different sounds to the characters than their normal Japanese readings, due to it originally being based on an earlier stage of Northern Ryukyuan that has not yet undergone vowel raising characteristic of the modern languages.
The poems contained in the compilation vary, but follow a general pattern of celebrating famous heroes of the past, from poets and warriors to kings and voyagers.
Nakahara Zenchū, on the other hand, traced it back to the Ryukyuan umuru, or umui, which comes from mainland Japanese Omoi(思い) meaning "to think" or to "feel".
Many of the Ryukyuan islands, largely culturally and linguistically isolated, are mentioned, along with various locations in Japan, China, Southeast Asia, and the South Seas.
The vast changes in Ryukyuan culture and language over the last several centuries have made the poetry difficult to access and understand, and Iha Fuyū (d. 1947) and Nakahara Zenchū (d. 1964) were among the only ones to extensively study it.