Shortly after I started reading I listened to a podcast in which the author kindly explained what the novel was all about. Saved me a bit of bother, but also the pleasure of working it out for myself. Anyway, spoilers ahead! Ishiguro's big theme is the trade-offs that come with (to use international relations terminology) post-conflict reconciliation. The Britons under King Arthur are responsible for crimes against humanity in their war with the Saxons. Gawain is charged with defending a dragon enchanted by Merlin to spread a fog of forgetfulness across the land, which prevents the Saxons from remembering the injustice they have suffered. The loss of memory keeps the peace, but allows war criminals to go unpunished. This grievance is the "buried giant" of the title. Ishiguro tries to keep the moral dilemma between peace and justice in balance throughout. To switch to Isaiah Berlin's terminology: the two values are incommensurable and the choice between them is 'tragic' in that it will involve evil either way.
Ishiguro makes a parallel between forgetfulness at the social and personal level. As with Saxon and Briton, so with man and wife. The elderly couple in the book have dark secrets in their past, which the enchanted mist has covered up. This memory loss has allowed their relationship to recover and grow stronger. However, as death approaches and the mist recedes, the past rises up and separates them. Love and harmony can only be sustained by willful acts of forgetting (if not forgiving). And yet those buried giants are never exorcised entirely, and are always liable to return. Should we face up to them? Again, the choice is tragic either way.
It's a clever conceit for a story. And apparently it came to the author before he settled on a genre. The Buried Giant has attracted interest because it is unashamedly a fantasy novel, with dragons and ogres, knights and wizards. I'll admit that this was the major reason why I picked it up. And yet it doesn't feel representative of what the genre has evolved into (plot-heavy literalist medievalism à la G.R.R. Martin or Robin Hobb). Ishiguro mentions samurai manga and the westerns of Peckinpah as inspiration. Gawain's ageing, honour-bound knight and the duel sequences definitely reflect that. Ishiguro has certainly also read Sir Gawain and the Green Knight, and other source material that fired up the imaginations of the Oxford Inklings. In fact, my sense is that the shadow of Tolkien hangs quite heavily on The Buried Giant, particularly the Hobbiton-esque community at the beginning and the Grey Havens vibe of the boatman at the end.
This is nowhere more apparent than in the voice Ishiguro uses, which mimics the anachronistic way Tolkien describes the dragon firework at the beginning of Fellowship as "like an express train". Ishiguro speaks directly to the modern reader at the beginning, in the same way that Tolkien does when he introduces you to hobbits. And as you are sucked into the story and get comfortable in its setting, the interjections fade almost imperceptibly away. Apparently, Ishiguro struggled with the narrative voice when writing the book (his credits his wife with urging a rethink). It's interesting that he went back to the source for a way out.