He was a son of Nanba Yoritsune (難波頼経, Japanese Wikipedia),[1] and the ancestor of the Asukai family, who were known for their skill at both poetic composition and kemari.[1][4] Being of Fujiwara stock,[1] he was also known as Fujiwara no Masatsune (藤原雅経).[2][3][4] Among his grandchildren was the poet Masaari.[5][6] He made a private collection, the Asukai-shū, which was posthumously edited by his grandson in 1292. Twenty-two of his poems were included in the Shin Kokin Wakashū, and a total of 134 in the imperial anthologies.
Masatsune studied waka under Fujiwara no Shunzei and from 1201[3] served in the Poetry Bureau (和歌所, Waka-dokoro).[1] He served as one of the compilers of the Shin Kokin Wakashū, along with Shunzei's son Teika.[1][2] Some twenty-two of his own poems were included in the imperial collection.[1] A total of 134 of his poems were included in it and later imperial collections.[3] He also compiled a private waka collection, the Asukai-shū (明日香井集, also called Asukai Wakashū, 明日香井和歌集[2]), which was edited by his grandson Masaari in 1292.[1]
The following poem by him was included as No. 94 in Teika's famous Ogura Hyakunin Isshu: