The poem in question here is KKS IV: 210, which is recorded in that anthology as being an anonymous ‘Topic unknown’ one. Its attribution to a poetry contest is made by Minamoto no Toshiyori (Shunrai) 源俊頼 (1055-1129), in one of his judgement Naidaijin tadamichi uta’awase 内大臣忠通歌合 (‘Palace Minister Tadamichi’s Poetry Contest’; 13th day of the Ninth Month, Hōan 保安 2 [26.10.1121]) where he states the poem is from a contest held in Kanpyō 9 [897]. Hagitani (1963, 93) acknowledges this attribution may be spurious, given that it seems unlikely the compilers of Kokinshū would not have mentioned the contest, had it been well known, but suggests deferring to Toshiyori’s expertise, given that he may have had access to materials which we do not.