Do we know of the existence of Japanese mythological texts that predate the Kojiki?

Question

The Kojiki (Record of Ancient Matters) is the oldest surviving work of Japanese mythology (and, indeed, the oldest surviving work in the Japanese language, period), and as I understand it, much of our understanding of early Japanese mythology (the creation myths, the mythological emperors, etc.) comes from it.

Do we have reason to believe that there were earlier, non-surviving written works that collected Japanese myths? For example, do any early texts claim that such-and-such story is narrated in some other work that we no longer have any copies of?

Answer 1

We know they existed, but not much else.

In fact, none other than the Kojiki itself states that its stories are collected from contemporary works (which have all been lost). This is because the Kojiki was a compilation. It was the product of a royal effort to collect "historical" texts in circulation at the time, to edit into a relatively coherent narrative. And propaganda.

From the Kojiki's own preface,

朕聞諸家之所藏帝紀及本辭，既違正實，多加虚僞。當今之時，不改其失，未經幾年，其旨欲滅。斯乃邦家經緯，王化之鴻基焉？故惟撰録帝紀，討覈舊辭，削僞、定實，欲流後葉

We heard that chronicles collected by other families are inaccurate and contains many fabrications. If this is not corrected now, within a few years the true message would dissipate. Therefore we compile this chronicle, examine the old tales to remove false narratives and pin down the truth for the future.

Thus, it is certain there were earlier works, but unfortunately none has survived. The Kojiki (and later the Nihon Shoki were somewhat political in nature for justifying the legitimacy of the ruling house. Thus natural attrition due to time and lack of government patronage aside, contrarian records likely faced a hostile environment when it comes to preservation.