Ever since I started to study kagura, my question is "what is music of kagura?".
My great-uncle is shinto priest living in big Shinto Shrine near my home. One day, when I was at age 5, I visited him with my grand-mother and listened to the weird music. Kagura dansers were doing rehearsal before the annual ceremony. I started classical music lesson at age 2. For me, it didn't sound like music, but something another (indeed, it's pentatonic and totally different from Beethoven works.) I wanna point out the point that the person who has classical music training, didn't consider it as music.
Later at the university, I started musicological classes, and noticed that kagura is not the musicological issue. Any class treated kagura. At least 20 years ago, the kagura is out of main interest of musicologists (still now). I even heard saying "kagura is musically not interesting".
The word "music" is very conceptual, for the people being familiar to the tonal music, pentatonic is not exactly music.
However, I noticed that it is not only musician problem. When I started my fieldwork, I noticed that local kagura musician doesn't think their sound production as music, neither.
Why?
Actually, the word "music" is translation, as I know, German translation into Japanese. To explain new words into Japanese language, Japanese looked up suitable words in Chinese classics. The music seems to be one of them. At school, we learn classical music as music and no Japanese traditional music (until 2000.) Before the creation of the term "music", there were music, of course, but it had been for long time recognised as another term, hayashi.
The kagura musician considered their production as hayashi, and for them, the music is classical music. In short, kagura music doesn't exist conceptually.
Next question which occurs after this conclusion, is if we can classify one genre of music as kagura music, musicologically? Kagura is ensemble of various genres of theatres (especially early Middle age). But it is rare case (or no one keeps) original music, but troop adapts local music. Even two troops have same dance piece, their music are often totally different. In this reason, we cannot say that kagura music doesn't exist musicologically, neither.
My next question is, so the, why specialist classify certains rituals dances as kagura? What is condition to consider one dance as kagura?
Actually, I personally think that it exist no melodic/rhythmic crue to define one dance as kagura. This is why I tried to find the commun point between totally different exemples for my Ph. D dissertation. I think I already rewrite over 20 times about this, but I still don't find logical explanation, why kagura exists or doesn't exist. It exists because one day, specialist classified in this way .... And no one tells that it is wrong.
Even though, something called as kagura exists. We can re-define it with another explanation...