PROLOGUE

"Taken from the underground holding cell and led up by elevator, I was ushered into a room at the end of the corridor on that floor. The fluorescent lights clinging to the ceiling were dimmed to an extreme, making the gray walls create an atmosphere as suffocating as a solitary cell. From early morning until late at night, I was rigorously interrogated day after day. However, that morning, the room where Kohei was taken was different from the previous ones. It had a window, albeit one covered with a smoky film and secured from the inside by bars, but light from outside managed to seep into the room. It had been two weeks since Kohei had seen sunlight.
The two interrogators waiting in that room were strangers to him. When the two guards who brought him in unlocked the rope and handcuffs that bound Kohei's body and left the room, the elderly interrogator gestured for Kohei to sit and said something peculiar.
"It's been a while, hasn't it, Mr. Yoshida?"
Kohei, with tired eyes, gazed back at the man."
"It's been about ten years, hasn't it, since we've faced each other like this. You've probably long forgotten about me, but I remember you well. When I heard you were arrested again, I've been curious for quite some time."
Upon hearing those words, for the first time, a vague memory of this person surfaced from the depths of his recollection. This person, now in his late forties or early fifties, deducting the ten-year gap, indeed left an impression of having faced this man like this before. Even back then, Kohei had confronted in that grey room.
The investigator who identified himself as Takaji Furuya, perhaps to sharpen Kohei's memory or maybe to exert further pressure, was reflecting on that time when the door was knocked, and a female police officer brought in coffee on a tray.
In that room, there was another desk for transcribing statements, and the man sitting at it accepted the tray, saying thanks. He placed the porcelain cup first in front of Kohei and then in front of Investigator Furuya. What could this possibly mean?
"This coffee is ordered from a local shop. It's been a while since you've had coffee from a cafe. Shall we start with a morning coffee break?" Furuya said, savoring the cup with gusto.
"Oh, delicious. Cafe coffee is always good. Please, while it's still hot, Mr. Yoshida," he continued, indicating the cup towards Kohei.
 "It wasn't uncommon for them to offer coffee. Throughout these past two weeks of interrogation, coffee had been placed in front of him several times. It was either from a vending machine within the station or poured into paper cups. The interrogator would say, 'This one's on me. Doesn't cost much, but it pays off,' as a tactic outlined in the investigative manual, stating that occasionally offering candy can be an effective method to smoothly extract a statement. But this morning, they deliberately ordered coffee from an outside shop and offered it to Kohei. Could this be a ritual to celebrate the completion of writing up all the reports and settling the matter?
Kohei sipped the coffee. For Kohei, whose body and mind felt rough, the taste of the coffee was neither good nor bad; it was merely a hot liquid streaming down his throat. However, that white porcelain cup triggered something within him. When he saw that cup, something akin to a gust of vitality swept in. From the depths of his depleted life, there was a faint emergence of sensual water, and he felt an urge to depict that cup."
 "Holding a 3B pencil, I draw the sensuous curves created by the cup onto Watson paper. The paper's rough texture seems to echo the smooth strokes of the 3B pencil. Those delicate lines were the essence of the sketch. It shapes the outline akin to caressing a woman's body. Then, I add shadows with a 5B. Strongly, lightly, intensely, gently. The sensuous skin emerges on the paper. Shadows produce light. The darker the shadows, the more light pours in.
"Mr. Yoshida."
As if severing Kohei's thoughts, Investigator Furuya stepped in. The men who had sat in front of Kohei until yesterday were like embodiments of criminal procedure law. They'd employ threats and intimidation, then abruptly switch to offering coffee, using coaxing tones, to craft their intended statement as per their schematic. However, this man seemed entirely different from the previous interrogators. He was more composed, exuded familiarity, and occasionally addressed Kohei respectfully as 'Mr. Yoshida'. This increasingly perplexed Kohei.
"We received an anonymous letter at the investigation headquarters. I wanted Mr. Yoshida to read this letter first."
 As Kohei didn't reach for the envelope presented by the investigator, Furuya took out the letter from the envelope himself and unfolded it while speaking.
"It's a letter from a woman. Seems like someone who knows you well. This letter arrived at the investigation headquarters quite a while ago but remained buried under a mountain of related documents, still sleeping. Finally, this letter has woken up from its slumber. It should encourage you. It's a letter claiming that the truth is here. Please, take a moment to read it."
In a somewhat resigned manner, Kohei reluctantly took the offered stationery. He glanced at the contents of the letter. It bore gracefully flowing, beautiful handwriting. The text seemed to flow effortlessly, likely rewritten multiple times. It was a letter laden with the urgency of needing to express, needing to convey. Kohei slowly read through the five pages of the letter, as if to confirm each and every word. However, none of those words managed to penetrate his mind. What he felt upon finishing reading was not the content of the letter but rather the question of why this letter was being made him read it now, after all this time.
 After folding the stationery and returning it to Investigator Furuya, he further inquired, almost probing into Kohei.
"How was it? Wasn't this not what you wanted to tell us? Wasn't what you wanted to scream about not written here?"
"……………"
"Mr. Yoshida, I shouldn't be discussing these things, but I'll be honest about the situation. It seems this case isn't what we initially thought. It's far more complicated, entangled with multiple layers of secrets or rather, traps. To be frank, it seems we've somehow messed up the investigation. So, we're starting the investigation anew, going back to square one, redoing everything, which is why I'm here talking to you."
"……………"
"Essentially, after taking quite the detour, we've finally reached the starting line to uncover the truth. This means, Mr. Yoshida, that you're now walking towards the exit of light, too."
What on earth is this man saying? What does this mean? Kohei knew their ways. Once they set a track, they never change it. Even if it became evident someone was innocent, once a death penalty verdict was reached, they would resolutely lead them to the execution platform. That was their way. Kohei had already experienced this. He was a victim of the iron tracks laid by them. In their world, as this man said, it was impossible for a last-minute turn to change the investigation, especially at the verge of the detention period.
Kohei wondered if this investigator might be conducting some kind of experiment. When a defendant stands in court, there are often sudden reversals in statements. Are they conducting such malicious experiments, anticipating such situations? Is this a scenario prepared to handle how Kohei might reverse his statement?
"Now, this is your new beginning. Please tell us the story of freeing yourself from this captivity."
 Kohei glanced at the cup again. What captivated his thoughts wasn't the enigmatic questions spun by the investigator but the white cup itself. He desired to sketch the sensuous skin produced by the porcelain and soft curves reminiscent of a woman's body.
"Is it my story?"
He stated, consolidating a singular intention emerging within him.
"Yes, your story is what we need right now."
"It's a very long story."
"No matter how long it is, I must hear your story."
"If you insist, shall we give it a try?"
"Yes, please do share. We have plenty of time. It doesn't matter how many hours it takes. I want to listen carefully to your story."
Kohei cradled the cup in both hands. What a soft touch it had. What beautiful curves. He thought perhaps it wasn't the hand of God that created these curves. And as he sipped the hot liquid, he began.
"Detective, you are familiar with the plane tree, of course."
"Plane tree?"
"Yes, a plane tree. Do you know the scientific name for this plane tree?"
"No, I don't know it."
 "In Japan, there are three types of Zelkova trees: Zelkova Serrata, Zelkova Serrata var. miyabeana, and Zelkova carpinifolia. From their appearance alone, it's quite challenging to discern their differences. However, upon closer observation, there are clearly distinct features among these three trees. Firstly, their large leaves differ."
"The Zelkova Serrata, right?"
"Yes, Zelkova Serrata."
The other investigator, who had a ballpoint pen in hand, started noting down Kohei's statement. He paused, wearing a perplexed expression directed at Kohei.
"Zelkova Serrata and Zelkova Serrata var. miyabeana have their leaf tips divided into five parts with deep clefts. However, the leaf lobes of Zelkova carpinifolia are in three parts, and their leaf tips have much shallower divisions."
"I see, I understand."
Investigator Furuya nodded as if showing interest.
"During autumn, there is an even more decisive difference. At that time, elongated fruit stalks emerge from the branch tips, carrying hard, spherical fruits. Zelkova Serrata and Zelkova Serrata var. miyabeana bear their round fruits on the fruit stalk in pairs of two or three, and in some cases, five or six. However, Zelkova carpinifolia only bears a single fruit on the fruit stalk."