"A, B, C. We're certainly relying on basics tonight. But proceed."

「全く芝居じみている」　俺はいった　「アガサ・クリスティの世界だな。容疑者を集めて探偵が推理を披露をするわけだ」

「クリスティの世界なら、もう少し話が派手になるでしょう。容疑者も多い。この部屋の壁沿いにずらりといすを並べる必要があるほどにね。しかし容疑者が三人だからといって、犯人を絞るのが楽だというわけでもないのが、捜査の難しいところです」
『私が彼を殺した』

"This is all quite theatrical," I said.  "Like something out of Agatha Christie. With all the suspects gathered and the detective who is going to unveil his deduction".

"This story would be a bit more grand if this was Christie. With more suspects. Enough so we would have needed to line up chairs along the wall of this room. But the difficulty in these investigations is that even with only three suspects, it's not easy to narrow it down to the one murderer." 
"I Killed Him"

The Challenge to the Reader is something I've enjoyed since... always? Dutch comic book readers might remember comics like Inspecteur Netjes (with the legendary "Weet jij het ook?!!" ("Do you know too?!!") - challenge) or even Disney's Sul Dufneus (Shamrock Bones) and Mickey Mouse detective comics, which always ended with a challenge to the reader. Manga like Conan and Kindaichi Shounen do it more indirectly, as the protagonists of both series usually announce when they have solved the riddle (and thus suggest that you should have been able to solve the case too by now).

Higashino Keigo's Dochiraka ga Kanojo wo Koroshita ("One of the two killed her") played with this: the novel revolved around two suspects, but it is not made clear the novel itself who the real culprit is: it is up to the reader to deduce it. It works out precisely like a normal detective, with clever hinting and all, but the conclusion just avoids any words that point to specifically to one of the two suspects (using words like 'that person' or 'the murderer' to refer to the culprit in its denouement). You have all the necessary clues in your possession, so solve it yourself. The ultimate challenge.

Kaga Kyouichirou series
Sotsugyou ("Graduation") (1986)
Nemuri no Mori ("Forest of Sleep") (1989)
Dochiraka ga Kanojo wo Koroshita ("One of the Two Killed Her") (1996)
Akui ("Malice") (1996)
Watashi ga Kare wo Koroshita ("I Killed Him") (1999)
Uso wo Mou Hitotsu Dake ("One More Lie") (2000)
Akai Yubi ("Red Fingers")  (2006)
Shinzanmono ("Newcomer") (2009)
Kirin no Tsubasa ("The Wings of the Kirin") (2011)
Inori no Maku ga Oriru Toki ("When the Curtains of Hope Come Down") (2013)

Watashi ga Kare wo Koroshita ("I Killed Him") is the spiritual successor to that book and the fifth book in the Kaga Kyouichirou series. Like it's predecessor, the identity of the real culprit is not made clear in the novel itself, instead giving the readers the ultimate challenge: deduce it yourself. The story starts the day before the wedding of popular writer/movie director Honami Makoto and poet Kanbayashi Miwako. A little gathering at Honami's house is disturbed by a woman dressed in white; Honami's former lover Namioka Junko, who now knows that Honami has betrayed her. They get rid of Junko quickly (in the non-criminal way) and preparations for the wedding proceed as planned. The wedding the next day itself is kinda ruined by Honami dying just when he entered the chapel; being poisoned by strychnine. As Junko has committed suicide the day before (also with strychnine), the police at first suspects that the ex had poisoned Honami and then commited suicide as forced love suicide.

Kaga of course doesn't agree with this and finds three persons who had access to the strychnine and the opportunity to switch Honami's medicine with the strychnine-laced medicine: Kanbayashi Takahiro, brother of Miwako who had an incesteous relation with her. Suruga Naoyuki, Honami's manager who was in love with Junko and hated how Honami had treated her. Yukizasa Kaori, Miwako's agent who once had been Honami's lover herself. The murderer is one of the three, but who?

The novel is written from the perspective of the three suspects, switching between them as the plot develops. This makes for some interesting reading, as you actually know that one of the three must be the murderer. So you already know that the narrator=murderer trick is being used. The murderer doesn't outrageously lie to the reader, but just manages to avoid mentioning crucial parts (like saying "and this is when I did it..." or something like that).

The novel ends with the single line "the murderer is you" uttered by Kaga and I can imagine that many people could have missed the solution. I missed it myself, so I had to look it up on the internet to check. It was not as devious as in Dochiraka ga Kanojo wo Koroshita, which was really well done, but a decent one. It's a bit of shame that the solution hinges on the final revelation by Kaga (so you really can't solve it until the last page and you can never win from Kaga), but with that final clue in your hands, it's actually quite logical and I think I would have solved it if I had re-read the book again (of course, that's easy to say now). It seems by the way that the murderer in the seralized version and the hardback/paperback versions differ. In the paperback version, the novel is followed by a set of sealed pages, which contain hints to the murderer, but I really, really don't want to cut in my books...

And it seems that Higashino Keigo already has an idea to follow up this series of One of the Two Killed Her, I Killed Him with a third part, You Killed Somebody, so I'm looking forward to that!

Original Japanese title(s): 東野圭吾　『私が彼を殺した』