I very rarely stop reading a book before I've finished it. This happens perhaps once or twice a year, and usually because of boredom more than anything else. This is the case with Emperor of the Eight Islands. It's not because the writing is bad; it's lyrical and descriptive, evocative of medieval Japan and respectful to its distinct culture. And it's not because nothing happens; the plot moves along briskly, with plenty of action. It's just...boring. Perhaps there is actually too much going on, by which I mean that so many things happen, it's hard to care about any one of them. Nephews are murdered, old men's eyes put out, wives passed between brothers - there's so much happening and so many main characters that it's difficult to focus on any one of them. I was halfway through the book and a year had passed without me giving a hoot whether the central main character lived or died. And perhaps the problem lies in that very character's blankness. Shikanoko has plenty to be pissed about: a dead father, a treacherous uncle, romantic jealousy, a stolen land. But none of these things seem to actually motivate him to do anything other than attach himself to the strongest lord around and take his orders. He's a nonentity.
This is a multi-book series, so maybe it just takes a while to get to the meat of the story. But if an author wants readers to pick up books 2, 3, and 4, she needs to hook them in book 1. Hearn failed to do so, with this reader at least, so I'm giving up and moving on.