The , often abbreviated as Shūishū, is the third imperial anthology of waka from Heian period Japan. It was compiled by Emperor Kazan in about 1005.Keene 1999 : 283 Its twenty volumes contain 1,351 poems. The details of its publication and compilation are unclear.
The Shūishū was an expansion of Fujiwara no Kintō's earlier anthology, the , compiled between 996 and 999. Until the early nineteenth century, it was mistakenly believed that the Shūishō was a selection of the best poems from the Shūishū, and so the former was more highly regarded.Keene 1999 : 284
The second poem from the 'lost' poetic sequence of Priest Manzei can be found in this anthology.https://historyofjapan.co.uk/wiki/priest-manzei/
References
Bibliography Cranston, Edwin A., 1993. A Waka Anthology, Volume Two: Grasses of Remembrance. Palo Alto : Stanford University Press. . Keene, Donald, 1999. Seeds in the Heart: A History of Japanese Literature, Volume 1. New York: Columbia University Press. .