I now have the kanji and furigana for the twelve astrological signs/ hours written on the flyleaf, plus the kanji for north-east (ushitora, it's read, because it comes directionally between the ushi and the tora) and southeast (read tatsumi for reasons best known to the Japanese) and several others I cannot now recall. Everything in onmyoudou maps onto everything else- wheels within wheels and all spinning merrily, as they say- hours onto seasons, seasons onto directions, directions onto elements, elements onto colours. The one thing I *don't* yet know is how come there are only 12 astrological signs. This is a lunar calendar, and there are either 13 lunar months in a year or the seasons get badly out of synch in very short order, and we go picking first shoots of spring as the autumn leaves fall.
Of course, the ahem pedantic nature of vol 6 may be the reason why it was the only one available at Mandarake any time I looked.