Impossible Crimes, Time After Time: THE LAPIS LAZULI CASTLE MURDERS (2002)

"All living things in this world go to war. It doesn't matter if they're big or small. As long as life exists, we'll all keep killing each other."

Two lovers reincarnate in an endless cycle across history, destined to always find one another, cursed to always kill each other with the same dagger. Not a premise you look at and think "sounds like a fair-play locked room scenario", but that's exactly what you get in The Lapis Lazuli Castle Murders, an unconventional detective novel by Takekuni Kitayama. It's the second book in his Castle series, which could be compared to Yukito Ayatsuji's Mansion series (each case is themed around a weird castle) except that as far as I'm aware, the detective doesn't carry over.

Kimiyo is a young librarian suffering from terminal brain cancer. One day, the mysterious Kito comes to "the Library at the End of the World", claiming that Kimiyo was his lover in a past life, that she was once a princess named Marie and he was her loyal knight Raine. While Kimiyo is initially skeptical, she can't deny the magnetic sense of familiarity and half-remembered dreams. Her colleagues at the library attempt to help her piece together the history of the cursed daggers and the impossible events surrounding them. From there, we jump to two historical encounters between Raine and Marie's incarnations: a set of bizarre decapitations and vanishing corpses at the titular castle during the Albigensian Crusade, and an eerily similar incident in the French lines at Verdun.

Fair-play mysteries with supernatural elements are a subgenre to themselves at this point (particularly in video games), but to make it work the audience has to know what they can trust as "real". Lapis Lazuli Castle does this by pragmatically explaining away an impossible incident in the very first medieval chapter. Further impossibilities are introduced and explained progressively over the course of the novel.

You might think from the premise that the Library at the End of the World is the grounding element for the audience, a framing device for the historical murders. This is eventually proven wrong, with as much carnage as possible, when the library serves as the setting for a multi-dimensional locked room murder that is the most grisly of the lot. Reading this, it suddenly made sense that Kitayama went on to write for the Danganronpa series.

There is still a distinctive supernatural atmosphere, even apart from all the reincarnation stuff. Lapis Lazuli Castle has a strange, almost hallucinatory setting. Even the library, the modern plotline, seems removed from reality:

When she began to doubt his attitude, everything about the Library at the End of the World began to look like the set for a stage play. She looked at the door. Was that door so noisy because it was a cheap, hastily set up prop?

Time is similarly vague and fuzzy:

A red circle marked the 25th, but as far as she could remember, that wasn't the date.

(And no, it's not because Kimiyo's brain tumour is causing her to imagine the entire plot.)

The strangeness rolls over you like a warm bath, making you want to go with the flow, so that by the time a reality-hopping, foul-mouthed, genderless "angelic detective" arrives on the scene to tie all to tie all of the cases together, you're ready to go "Yeah, why not?" My closest comparison point would be Umineko: simultaneously completely fair play in the mysteries, but also overtly supernatural in a way that is eventually the main focus of the plot.

The locked room tricks are all quite good (and some connected). It's highly mechanical stuff that reminds me a bit of Soji Shimada's work. The library case is the most jaw-dropping in its intricacy, but I think my favourite was actually the headless knights case at the eponymous castle. To be honest, the fact that all of these tricks land is impressive in itself.

So, you have (by my count) seven impossible crimes, a reincarnation-flavoured meta-plot, and eventually active time travel. That's a lot to pack in to a slim volume, and that's the only real weakness of the book. To draw another comparison between Lapis Lazuli Castle and Umineko, I've always felt that Umineko does not justify its length (word count) but absolutely justifies its length (arcs). Almost nothing overtly magical happens in the first arc. The second arc introduces the meta-game between Battler and Beatrice. The third arc turns the format on its head, etc. It takes a while to acclimatize oneself to the rules of an SFF mystery, and in Umineko you do go through an entire mystery before the rules are tweaked each time. Lapis Lazuli Castle, by comparison, is breakneck. I barely had time to register the rules of reincarnation before new twists were being added. It felt like my head was being knocked around. It would make a good 12-episode anime series, you know? A little more time with the characters in all the different timelines would go a long way to absorbing what is going on.

Still, I really liked this book. It's original, and the mystery tricks are complex. I'd love to check out the other entries in the series, particularly Clock Castle.