2
The trio walked out onto the seashore.
They climbed down to the breakwater and sat next to each other on one of the concrete tetrapods poking out of the water.
Beneath the bright sun the calm sea offered a stark contrast to the state of their minds.
‘So they all died.’
Kawaminami’s arms shivered as he sat down hugging his knees.
‘I’ve been an idiot.’
‘Conan,’ Shimada called out to him. Kawaminami shook his head several times.
‘We went around, poking here and there, but what did we accomplish? Absolutely nothing. We even came to this very harbour just three days ago. We should have at least warned them on the island then.’
‘It’s not your fault.’ Shimada stroked his chin and said, as if to himself:
‘How many people would have taken those letters seriously and gone running around as we did? Even if we had gone to the police, they would have simply said we shouldn’t take such things seriously and kicked us out.’
‘I wonder.’
‘I kept saying Nakamura Seiji was still alive and, in all seriousness, everybody on the island was in danger, but that was all I did. I couldn’t cross the sea and go to the island just because of a guess, not without some decisive evidence that showed that everybody on the island was indeed in danger of being murdered.’
‘Mr. Shimada,’ Morisu interrupted. ‘If everybody on the island has been murdered, does that mean that Nakamura Seiji is indeed alive?’
‘Well, I wonder,’ Shimada said evasively.
‘But who else could the murderer be?’
‘Who knows?’
‘Mr. Shimada, what’s your opinion of those letters signed by Seiji? Were they related to what happened on the island?’ Kawaminami asked.
Shimada grimaced:
‘We can only assume they were, considering what has happened since.’
‘Is the same person behind the fire and the letters?’
‘Yes, I believe so.’
‘Were the letters a warning?’
‘I don’t think they were a warning, exactly, and it was curious they were delivered right after everyone had left for Tsunojima. I think the murderer had some other purpose in mind.’
‘Such as?’
‘Conan, on the first day we met, you made an analysis of your letter and came up with three different meanings. Do you remember?’
‘Yes. Accusation. Threat. Look into the Tsunojima accident of last year again.’
‘Yes.’
Shimada gazed sombrely at the sea.
‘Following that suggestion, we started a second enquiry into the incident that happened last year and managed to uncover the truth behind that. But I don’t believe the culprit had foreseen that. The sender could not have guessed that we would actually be so meddlesome. So I think the culprit’s real intentions with the letters was to accuse you of murder and to suggest the idea of Nakamura Seiji to us.’
‘Nakamura Seiji?’
‘By signing as Nakamura Seiji, he planted the idea in our minds that the dead architect was actually still alive. The goal of that was, of course, to turn Seiji into a scapegoat.’
‘So Mr. Shimada, the person you are suspecting is….’
‘Nakamura Kōjirō?’ Morisu asked carefully. ‘You mean that now we know that Nakamura Chiori is Mr. Kōjirō’s daughter, the person with the motive to kill everyone is not Seiji, but Mr. Kōjirō.’
‘Going by motive, I agree that Mr. Kōjirō is the prime suspect. But—.’ Kawaminami glanced at Shimada. ‘—But he was in Beppu all the time.’
‘Conan, do you remember what that young man said?’
‘Eh?’
‘The son of the fisherman who took your Mystery Club friends to the island.’
‘Ah, yes.’
‘He told us that it wasn’t difficult to go up and down the island in a motorboat. Can you be sure Kō didn’t do just that?’
‘Oh.’
‘Kō said he had been cooped up in his house the last few days to write a thesis, and shut out all visitors and phone calls. But was he telling the truth?’
Shimada nodded slightly, still staring at the sea.
‘Yes. I find it hard to say this as his friend, but I have to suspect Kō. He lost his daughter, the only bridge between him and his unreachable love, and in such an awful way. And because of her death—remember what he told us?—his love was murdered by his own brother. He has more than enough of a motive.
‘And Kō was also the previous owner of the Decagon House. It’s not too farfetched to imagine he somehow managed to hear that the people responsible for his daughter’s death were going to the island. He wrote those letters to you to suggest Seiji was still alive, divert suspicion to Seiji and to vent his own pent-up rage. He sent one of those letters to himself, too. To make him appear to be one of the victims as well.’
Now all three of them were looking silently at the sea.
‘I agree,’ said Morisu finally, in a dull voice. ‘He’s the only one I can think of with a motive to kill all of them, on that island of all places. Mr. Kōjirō is the most likely suspect. But Mr. Shimada, this is nothing more than conjecture.’
‘I know, Morisu,’ Shimada answered ironically. ‘It’s nothing more than conjecture. And, rest assured, I have no intention of looking for evidence. Neither do I plan to tell any of it to the police.’
Noticing two boats appearing from beyond J—Cape, Shimada stood up.
‘Police boats. They’re coming back. Let’s go back in.’