In the world of dynastic poems, "kashu" is a collection of waka (a traditional Japanese poem of thirty-one syllables) compiled from personal or family poems. Also known as 'Ie no shu,' kashu is simply a name which tries to mimic the Chinese pronunciation. Poems could be selected either by the poets themselves or by others. In the early days, descendants usually edited their ancestors' kashu until self-selected collection of poems became more mainstream between the Insei period (the period of cloistered Emperors) and roughly around the Shin Kokin period (c. 1205). During the Kamakura period, kashu's popularity matched that of the Chokusenshu (the anthology of poems collected by Imperial command).
The four oldest examples of kashu: Hitomarushu (the Collected Works of KAKINOMOTO no Hitomaru), Akahitoshu (the Collected Works of YAMABE no Akahito), Yakamochishu (the Collected Works of OTOMO no Yakamochi), and Sarumarushu (the Collected Works of Sarumaru Dayu) were compiled around the early tenth century. These were all compiled from poems appearing in or after the Volume 14 of the Manyoshu (the first major anthology of early Japanese poetry). Although there were discrepancies such as poets not originally named in the title appearing within the kashu, it could be interpreted as an important example of the shift in the readers' interest from reading anthologies to reading works of individual poets. It can be said that the people's interest in kashu grew about the time when Hitomaro and Akahito were being revered as 'kasei's (great poets).