The storage room was smaller than expected, barely big enough for two people to stand side-by-side. Okabara Kyogumichi's headlamp swept across the walls, revealing that they were made of heavy steel plates, covered in fine scratches, as if something sharp had scraped them over a long period.
The half-human-height metal box was placed in the center of the storage room. The dark red stains on its surface had dried and turned black, and a faint smell of rust mixed with blood could be detected upon closer inspection.
The top of the box had a circular dial engraved with the symbols of the Twelve Earthly Branches. In the center of the dial was a small keyhole, its shape perfectly matching the eye of the fox mask.
Kyogumichi didn't act immediately but looked back at Yoshida-sensei, who was slumped in the puddle. He was still muttering to himself, his eyes as hollow as two dry wells.
"What kind of experiment did Principal Sato conduct?" Kyogumichi's voice was exceptionally clear in the confined space. "What did Chitanda Nao see?"
Yoshida-sensei trembled all over, as if awakened by the question. He looked up, a flicker of fear in his cloudy eyes, quickly drowned by despair: "That wasn't an experiment... it was a sacrifice..."
"Sacrifice?" Kyogumichi frowned.
"Principal Sato joined a cult when he was young," Yoshida-sensei's voice was terribly shaky. "He said the Drama Club children were 'chosen vessels,' meant to communicate with the 'Shadow God' through the Shadow Box... That night, he locked six children in here, including Nao..."
Chitanda Eru's gasps came through the headphones, laced with an uncontrollable sob. Kyogumichi could imagine her expression at that moment—the girl who was always full of curiosity must be covering her mouth now, desperately trying not to cry out.
He took a deep breath and aimed the right eye of the fox mask at the keyhole in the center of the box. With a soft click, the dial began to vibrate slightly. Kyogumichi turned the dial according to the "Zi Chou Yin Mao" sequence mentioned in Chitanda Nao's cousin's letter. Each time he turned to an Earthly Branch, the sound of gears turning came from inside the box.
When the last symbol clicked into place, the metal box suddenly emitted a low hum, and the lid slowly flipped open. A blast of cold air mixed with a strong smell of decay gushed out. Kyogumichi instinctively took a step back, the beam of his headlamp steadily illuminating the inside of the box.
There were no strange objects inside, only six glass bottles with names on them, each containing a yellowed paper scroll soaking in liquid. The topmost bottle was labeled "Chitanda Nao," and a corner of the scroll revealed delicate handwriting.
Kyogumichi put on gloves and carefully took out the bottle. The cork had long since aged and came off with a light pull. He pulled out the scroll and unfolded it. The writing was somewhat blurred from being soaked, but the content was still discernible—it was Chitanda Nao's diary.
"September 15th, Principal Sato said he had a surprise for us and made us wear special masks..."
"September 16th, the masks couldn't be removed, my face is so itchy, it feels like something is moving under my skin..."
"September 17th, Kobayashi started talking nonsense, he said he saw shadows laughing in the masks..."
"September 18th, they all stopped moving... the Shadow God is calling my name..."
The diary ended abruptly here, the last few words covered by dark red stains, like splashes of blood. Kyogumichi's hand holding the diary trembled slightly. He finally understood who had left the graffiti on the walls—it was the children trapped here, their desperate cries written with their fingernails and blood.
"How did Nao survive?" Kyogumichi's voice was tight.
"She bit her own wrist and drew reverse runes on the ground with her blood," Yoshida-sensei turned his head, not daring to look at the box. "Principal Sato said she 'blasphemed the Shadow God' and sent her to a mental hospital... I was afraid of being implicated at the time and didn't say anything..."
The sound of something heavy falling came from the headphones, followed by Chitanda Eru's tearful cry for help: "Okabara-san... Yoshida-sensei's assistant is here... He locked me in the warehouse..."
Kyogumichi's heart sank. He looked towards the passage entrance, where there was only pitch black, but he could vaguely hear hurried footsteps approaching. His danger perception wildly warned him.
"It's Sato's old subordinate!" Yoshida-sensei suddenly shrieked. "He knows we opened the Shadow Box and wants to silence us!"
Kyogumichi quickly stuffed the diary into his pocket and closed the lid of the box. He looked around and found a ventilation duct in the corner of the storage room, just big enough for a person to crawl through. "Chitanda-san, listen," he said urgently into the microphone, "There's a fire axe in the warehouse, in the second cabinet behind the door. Smash the transom window and jump out. Go to the student council and find Kaguya Shinomiya; she can protect you."
"What about you?" Chitanda Eru's voice was tearful.
"I have a way to escape." Kyogumichi's gaze fell on Yoshida-sensei. "Take care of yourself."
He finished speaking, took off his headphones, and put them in his clothes pocket. The footsteps at the passage entrance grew closer, accompanied by heavy breathing. Kyogumichi shouldered his engineer's shovel, and the beam of his headlamp cut a sharp arc in the darkness.
When the man in the black suit rushed into the basement, what he saw was not a panicked teenager, but a side kick that whistled through the air. The kick sent the man sprawling to the ground, his forehead pressed against the puddle, looking extremely disheveled.
"Hand over the Shadow Box!" The man wiped the water from his face, enduring the pain throughout his body, and pulled out a folding knife from his pocket. A cold glint flashed in the darkness.
Kyogumichi didn't speak. He could feel that the other party was determined to fight him, and he was afraid that increasing his strength might cause a fatality. Just as the two were at a standoff, Yoshida-sensei suddenly scrambled up from the ground and, like a madman, lunged at the man: "It's you! You were the one who helped Sato bring the children here back then!"
The man stumbled from the lunge, and the folding knife clattered into the water. Kyogumichi seized the opportunity, gave each of them an extra shovel strike, and then turned and squeezed into the ventilation duct.
The duct was covered in dust and cobwebs. He could only crawl forward, hearing Yoshida-sensei's screams and the sound of heavy objects colliding behind him.
After crawling for an unknown amount of time, a glimmer of light finally appeared ahead. Kyogumichi pried open the grate of the vent with his engineer's shovel and jumped out—it was actually the old school building's boiler room, filled with the smell of coal smoke.
He pulled open the side door of the boiler room. Outside, the setting sun was slowly sinking below the horizon, painting the sky a golden red. Kyogumichi leaned against the wall, panting heavily, the diary in his pocket pressing painfully against his chest.
Police sirens could be heard in the distance, growing louder. Later, Kaguya Shinomiya informed him that Yoshida-sensei and the man had been taken to the police station.
Kyogumichi looked up in the direction of the Drama Club activity room. There were no lights there anymore, so Chitanda Eru must have escaped safely.
He felt the glass bottle in his pocket; the paper scroll inside still seemed to carry the temperature of ten years ago. Kyogumichi knew that this matter was not over—although Principal Sato had passed away, the shadow he left behind clearly still loomed over the school.
The last rays of the setting sun fell on Kyogumichi's face, stretching his shadow long. He clenched his fists, his nails digging deep into his palms. Whatever those things hidden in the darkness were, he would not let history repeat itself.
Tomorrow, it was time to meet Chitanda Eru. Kyogumichi turned and walked towards the school gate, his silhouette appearing particularly determined in the twilight. Some truths must be uncovered by those who live; some sins must be ended by future generations.