The waves crashed against the reef beneath the cliffs, and the rumbling sound of thunder echoed in my ears.

The stalactite cave was pitch black. Being in it, it seemed that even his breathing, heartbeat, and even his vital signs were dissolved in this darkness...... But thanks to this, the other four senses of the two people in the cave have become more sensitive except for their vision.

Outside the cave, the footsteps and conversations of the three men gradually approached, and gradually became clear and discernible in the oppressive accompaniment of the waves.

But the first sentence alone made Nao's heart tighten.

"'Behind the snakes that fled in panic, a thousand needles were buried in the snake holes'...... Are you sure it's here?"

An unfamiliar female voice said.

"That's right, after all, this is the only stalactite cave related to the case from ten years ago. The voice of the Biga Sect rang out.

"Hey, I said you've been working on that puzzle for so long and you haven't been able to find a definite location?"

"What are you kidding! I also got this letter after Matsuchimeika died. It's a blessing to be able to find a location for something so vague. Higa Soji sneered, "And instead of complaining, don't you think you should thank the person who provided the clue to the treasure?"

"You!"

"Alright, we're not here to quarrel, we all have to get along!" a gentle male voice dissuaded, "and we do have to thank Soji-san, if it weren't for his invitation, we'd probably never know what was hidden on such an inconspicuous island—right, Shayazi?"

"Hey, the person who clearly solved the first two sentences of the puzzle is fighting you......"

Listening to the words of the man known as Jingdou, Sha Yazi muttered unwillingly, but did not continue to complain, "So, what should we do now, do we want to enter the cave?"

"It's useless to go into the cave now, right? After all, as Keito said, if it's not the 'Three Days and Moon Nights' as mentioned in the puzzle, there is no point in entering the cave. ”

"Although that's what I said...... But since we're all here, let's go in and get acquainted with the terrain. Jing Dou paused, and said with a little hesitation, "But Zong Cisan, your face is not very good, is it okay?"

"Ahh It's just that the wound on my head hurts a little, and it's not a big problem...... Well, no big deal. ”

Zongji said unnaturally.

Hearing Soji's explanation, Yuto who was hidden in the darkness took a deep breath patiently, but he didn't know what kind of turbulent waves were stirring up in the heart of the young policewoman beside him.

Why do they know that poem?

Didn't Ji Mingjia send her more than one person before he died!

How many people knew about the puzzle when she knew nothing?

Not only did she "invite" her to represent the Metropolitan Police Department, but she also sent a letter containing clues to the suspect in the case ten years ago, Soji Higa, if Matsuaki was really an accomplice to the case ten years ago, as he had guessed...... Then his intentions are worth pondering.

Nao stared solemnly into the dark void, and a mind-stopping speculation crossed her mind.

Just as she was thinking, the three people outside the cave made another move.

Soji Higa took a step into the cave and tentatively moved his feet from side to side, the soles of his shoes rubbing against the floor of the cave. Such a cautious movement provoked Sha Yazi to let out a sneer. Soji ignored her uncomfortable laughter, cautiously raised the flashlight and clicked the switch - Yuto, who was hiding not far from the entrance of the cave, was startled, stretched out his hand and quickly hugged the girl beside him and fell backwards - a sword-like white light swept through the place where the two of them were standing and pierced into the cave, breaking through a long line of darkness.

"That's amazing......"

Higa Soji muttered an exclamation of admiration from the entrance of the cave.

Jing Dou smiled when he heard this, "Of course. This is the professional equipment of the national scientific expedition team, even if it is underwater at a distance of ten meters, it is more than enough to explore the cave. ”

"It's more than enough to give the little devil who is afraid of the dark more courageous. Sha Yazi said sarcastically.

Soji glanced back at her and laughed out loud.

"I now know why you're still a third-rate treasure hunter. ”

"You, what do you mean!"

"Don't you understand such superficial knowledge?" Soji extinguished the light and tossed the flashlight in his hand, "There are thousands of fairy rats in this hole, especially this season - they are all in the □ period after hibernation, and the slightest sound or light can anger them - if you don't want to be disfigured, it's better not to use this thing." ”

"What is that?"

"It's a bat. Legend has it that the bats in the stalactite cave became immortal because they drank the water in the cave, so they are called fairy rats in China, representing 'blessing' and 'longevity'. A similar story can be found in the Ryukyus, which is heavily influenced by China. Jingdou answered her question and sighed in embarrassment as he looked at the pitch-black hole, "But it's nerve-wracking, it's all come this far...... How can we not alarm the bats into the hole?"

"I think we'd better solve the other puzzles first, or we won't get much out of the hole. For you antiques expert, this should be a simple task, right?" said Soji as he walked out of the cave.

"That being said, solving a puzzle is not like identifying an antique, it's not something that you can see through at a glance with professional knowledge and experience!"

"But the first two sentences of this puzzle, Jingdou, didn't you solve it quickly!"

Sha Yazi said with some disbelieving. Jing Dou smiled bitterly and shook his head, "That's because the 'Three Sun Moon Leaf Teapot' that appeared in the first sentence happened to involve my major, and the second sentence was also understood with the prompt of Sojisan, but the latter one is ......."

"Anyway, let's go meet that guy first, I can't think of a way to do it. ”

"That's all there is to it. Let's go to the shrine. ”

The three of them said as they left the entrance to the cave.

It wasn't until there was no sound outside the cave that two deep breaths could be heard in the dark cavern.

Yuukin was lying on his back on a stalagmite at an angle of about forty degrees to the ground, and he didn't make a sound of landing at the last moment, all thanks to the support of this stalagmite - but in order to prevent the light from shining in cold, he kept hugging Nao, who was forced to lie on him, until the tense nerves suddenly relaxed, and Yuuko realized the soft body that was hugged by his arms, the curves of the girl clinging to his chest, and ...... The warm breath that kept scratching at the socket of his neck.

(That's how this guy is...... Slender and weak, it's really a girl. ）

As if he had realized for the first time the fundamental difference between himself and her, he couldn't help but sigh in his heart, and at the same time, at this moment, a strange feeling that had never been before, which seemed to be mixed with joy and sorrow, rose from his chest, and in the silence, the sound of their staggered and undulating breathing suddenly gave him the illusion that time had frozen.

But before he could taste what that strange feeling was for that moment, the sound in his ears smashed frozen time to pieces.

“…… Am I supposed to be glad that you've finally recognized my gender?"

The girl's helpless voice came from the side of his face.

Only then did Yuto suddenly realize that he had spoken out what he was thinking, and his heart jumped, and he involuntarily relaxed the force that was pressing the back of her head against him. Nao raised her head and pushed Yuto's arm at a subtle angle, easily freeing herself from his tightly wrapped arms.

Yuto pursed his lips, and a touch of embarrassment quickly crossed his handsome face, but fortunately it was covered by the dark environment, and when he looked at it again, there was no clue.

But there was still a strange glow in the depths of the dark eyes.

Nao didn't get a response from him, and smiled unconcernedly, but the smile quickly faded again.

"The two men who came with Soji Higa seem to be antique appraisers and treasure hunters. She whispered.

In this way, it can be seen that participating in the bone-washing ceremony on the 10th anniversary of Higa Kenichi's death was not the purpose of Higa Soji's return to the island - the treasure was—and the eight-character bearded man who claimed to be a treasure hunter in the first place to send the injured Soji back to Akanehama-tei......

"Murderer plus treasure?"

Half-lying on the stone pillar, Matajiyuto suddenly sneered, the echo of the impact sounded extremely strange in the deep cavern, "It seems that there are quite a few things that hinder our movement. ”

"Hinder?" Nao's eyes flashed, and she shifted her gaze to the young man beside her, curling the corners of her mouth.

"It should be help—after all, it is much easier to find a disguised prey once it is active. ”

"Wait, you suspect it......"

Yuto propped himself up and looked at the girl beside him, and his eyes, which had gradually adjusted to the darkness, reflected a slender shadow standing sideways—the figure nodded as if he knew what he was talking about, facing the direction of the hole.

"Ten years ago, eight or nine times out of ten cases were related to the so-called treasure. And the puzzle they just talked about -- don't you have a little impression?"

“……”

Nao's voice was soft and calm, but when it reached Yuto's ears, it oozed a taste of ridicule for no reason. He opened his mouth to say something to justify, but in the end he nodded in that invisible, intangible, and extremely strong gaze.

"I've heard about this puzzle. To be exact, this is a poem that my stepfather used to read a lot during his lifetime, and he wrote it down to me when he realized that his time was near, telling me that there was an interesting mystery hidden in this poem...... That's all. ”

"Then you realize that the poem is not just an 'interesting puzzle', as your stepfather said, but a key to unlocking the treasure ground, so you send the riddle to Higa Soji under the guise of Matsuyoshi Mingjia in order to lure him back to the island, and at the same time send me the evil letter to lure me to the island to reveal the truth about the tragedy of ten years ago......"

Suddenly, Nao instinctively felt a hint of disobedience.

Thinking back to the day Higa Soji was injured, it seems that before he could meet the other two members, he was carried to Akahama Pavilion by the treasure hunter named Iwasaki Yuichiro, and his whole body was soaked with his luggage - it seems that his first stop on the island was Akanehama-tei, and the three fools who attempted murder received the news of Soji's return to the island, and ambushed him on the way to the guesthouse...... But how did they know the specific time when Higa Soji landed on the 6 Black God Island, and how did they arrive at the ambush site at that point in time?

You must know that at noon on the day of the incident, Youji Yuren was still going to the guest room to inform everyone to have lunch, even if he acted immediately after receiving the news of Soji's landing on the island, how could he calculate the angle of attack and complete the trap in the short ten minutes that the other party walked from the dock to the shrine?

Unless......

"You already knew that Higa Soji would land on the island at noon yesterday, didn't you?"

Nao lowered her voice and sizzled like a snake, her blade-like gaze as if it had broken through the darkness and pierced Yuto's soul.

"It's not all. You also know the course of his actions, the time and purpose of his actions, and the movements of his movements-that Iwasaki Yuichiro is with you, right? You lured him back to the island not to find out the truth at all, but to kill him in the first place!"

"What happened yesterday, what are we going to do...... Didn't you already know that? What are you still surprised about?"

In the face of her questioning, Yuto sneered disapprerovingly, "As for luring Higa Soji - flies will pounce on them one after another when they smell the stench, all I have to do is wave the fly swatter." To deal with that kind of guy, only use the so-called treasure clues that leak points...... Look, didn't you fly obediently?"

"So you think the treasure of Black God Island is a made-up joke with no possibility?"

Nao was both pity and annoyed at his thoughts, and almost sneered.

"Do you know what Momo Higa Soji was for killing ten years ago, what made him kill so many people, even with one of his own arms, you know?"

"Didn't you guess yesterday, excluding vendetta and love killing, there is only money killing. At present, it seems that the only clue that matches the wealth killing is the treasure......" Yuto paused, as if he had finally realized something. Although the words were questioning, the tone was contradictory.

"Is that treasure really ......?"

“……”

Nao stared at the boy opposite in the dark, listening to the frequency of the other's breathing and heartbeat, and a cool breath crept up the back of his spine towards the back of his head.

She knew that the other party was not lying.

But......

"Hey, Yuren. ”

Nao called his name in a rare and serious manner, "Who is the signature of the letter of entrustment you said you sent me before, and what is the content?"

"Of course it's me. That's what we talked about last night. ”

Yuto couldn't understand her sudden leap in thought, and asked a little strangely.

"What, what's wrong with that letter?"

"Questions, I'm afraid there are as many as mountains. ”

Nao chuckled softly, but the hairs on her back stood up like flags.

Who is it......

Who is such a person who knows the treasure puzzle and can replace or destroy the letter of the Yokiyo people?