Aishōka
Aishōka (哀傷歌) is a category of "waka" poetry. Loosely translated, it refers to "laments", but the precise meaning varied over the centuries. Originally it appears to have referred specifically to laments for the dead, but later came to include Buddhist poems on impermanence and even some love poems. Overview. "Aishōka" is a category of "waka" (poems in classical Japanese) based on the content of the poems. It is most frequently used in reference to "bu-date", division of "waka" anthologies into thematic books. "Aishōka" most typically are poems of personal reminiscence and lament. In the 8th-century "Man'yōshū" poems  of this type were categorized as "banka" (elegies). The 9th-century "Bunka Shūreishū" (an anthology of poems in classical Chinese) used the word "aishō" (哀傷). Many of the imperial collections include books of "aishōka", including the "Kokin Wakashū", the "Gosen Wakashū", the "Shūi Wakashū", the "Goshūi Wakashū", the "Senzai Wakashū", the "Shinkokin Wakashū", the "Shokukokin Wakashū", the "Shokusenzai Wakashū", the "Shokugoshūi Wakashū", the "Shinsenzai Wakashū", the "Shinshūi Wakashū" and the "Shinshokukokin Wakashū". The word "aishō" was already in use in the "Man'yōshū" to describe the themes of several poems. With the exception of one poem describing a banishment, all were  laments for the dead. In the "Kokin Wakashū", the term refers to poems written about the death of a friend or a relative, but by the time of the later "Shūi Wakashū" it had come to cover poems about the impermanence of things and such poems expounding specifically Buddhist principles. This shift in usage continued in later collections, and by the time of the "Shinkokin Wakashū" the category included a very large number of poems on impermanence. In the "Shūishō", the term was used to describe six poems at the end of the book of love poetry. The precise meaning  and boundaries of what constitute an "aishōka" are not certain and seem to have fluctuated, specifically grown broader, over time.