By Nagaru Tanigawa and Natsumi Kohane. Released in Japan by ASCII Media Works, serialization ongoing in the magazine Dengeki Bunko. Released in North America by Seven Seas.
In general, I tend to review books right after I read them, giving a very fast, right off the top of my head impression. This can be a strength, as most of my feelings are raw and there to be written down, be they good or bad, but it can also lead me to make snap judgments on things that need a little more time to sit and simmer. At the moment, however, I have a bit of a backlog, and thus some books are sitting waiting for me to get to them. And it's too bad for Amnesia Labyrinth, which I quite liked as I first read it, but now upon reflection I find is not as good as I thought it was.
The basic premise works, and is designed to be a bit creepy. Young man returns from a boarding school to the bosom of his rich estate, to be welcomed by his three friendly sisters. VERY friendly sisters. He appears to be vaguely indifferent to everything (almost a given, this is written by the author of the Haruhi Suzumiya books, but luckily as the story goes on Souji proves to be quite different from Kyon) and is dwelling on past events that we are not privy to beyond the occasional suggestion of what has happened. Meanwhile, at his new school, there have been a string of deaths, and a slightly eccentric girl tries to get his help in solving their mystery.
I'll touch on the good points first. The story unrolls itself very well, with the revelations being integrated quite well while preserving the air of mystery and horror that surrounds it. Having Souji as the 'hero' is quite interesting, and our sympathies wax and wane as we learn more about him and what he chooses to hide from everyone. That said, he's a horrible hero to identify with, mostly as he's sleeping with at least one of his sisters, and his family also appears to have supernatural abilities. This means that we start to empathize with the heroine, Yukako, who may be searching for clues simply because she's bored (shades of Haruhi), or due to a misplaced crush on one of the victims, but otherwise gives the impression that she's the only one who may live through this story.
The air of menace and horror is pretty good as well. The few flashbacks we see to Souji and his sisters as normal, smiling children just make their present-day smiling menace all the more unnerving. The use of doppelgangers is also intriguing, and makes us think back to the history Souji told us at the start of the book, and wonder how much of that we can take at face value.
That said, there's a few problems here. The art is non-distinctive, which is my polite way of saying incredibly dull. Sometimes this adds to the creepiness, but more often it makes you wonder why this even needed to be made into a manga at all. This ran in Dengeki Bunko, which is primarily a story and novel excerpt-driven magazines for Media Works, but has a few manga scattered throughout. Now, Tanigawa has held up his end pretty well - there aren't huge chunks of text in the manga that make you think they adapted this by simply having the artist read the book as he drew. At the same time, the art ADDS very little - it's just there to make it a manga, giving us just the basics.
And this affects the story as well. I keep talking about the matter-of-factness of the revelations, but this means that we have very few highs or lows. There's no shocks or bits of terror here - just mild people reacting with mild emotions to creepy things. If you're going to have the lead hero committing incest, you can certainly make it boring for HIM, but don't make it boring for the reader as well! The reason Haruhi succeeds so well is because Kyon's bland delivery is counteracted by a) Haruhi's over the top antics, and b) his angry retorts to those antics. Souji may have a tragic backstory, but this has closed him off to emotions, and Yukako is not a strong enough costar to make us care about her either.
So all in all I think the first volume of this is a mixed bag. I'm not certain whether it's still running in Japan - the 2nd volume came out there over a year ago, but various web sources don't list it as complete. Perhaps it went on hiatus while Tanigawa finally wrote the 10th Haruhi novel. In any case, if you like mystery, horror, or family secrets, you may enjoy this, but you may also find that on reflection it's shallower than you thought.