According to the postface of this book, however, he was ranked Jugoinoge (Junior Fifth Rank, Lower Grade), but in 807 (when he wrote the book), he should have been ranked Shorokuinojo (Senior Sixth Rank, Upper Grade).
ところが、本書の跋には「従五位下」とあり、807年(大同2年)当時は「正六位上」だったはずである。