The purpose of this paper is to clarify the usage of the Japanese complementizer koto in the Heian
period.
The Japanese complementizer koto was already used in the Heian period. But there are some differences
between the Heian period’s usage and the contemporary usage. The latter is a consequence of
the former’s change. But how it changed from the former to the latter has not yet been clarified.
Therefore as a basic research to clarify it, I investigated instances of complementizer koto in the tale
of Genji, a literary work of the Heian period.
As a result, I found two functions of the complementizer koto that are peculiar to the Heian
period. One is to express that an event of complement has not happened yet. Another is to emphasize
that an event of complement is serious and important to a subject.
These functions of the complementizer koto are relevant to the usage of koto having substantive
meanings.