Sobu University's library was nestled in the ginkgo tree grove on the easternmost side of the campus. The red-brick building was covered in ivy, and when one pushed open the oak door, the heavy wood would creak, as if recounting the passage of time.
The afternoon sun, filtering through stained-glass windows, cast colorful light spots on the floor. The air was filled with the unique scent of old books—a mix of ink and dust.
When Okabara Kyogumichi entered the library, Chitanda Eru was already seated by the window, a thick stack of architectural yearbooks spread open before her. She had her hair tied back in a neat ponytail, a silver hairpin clipped to her forehead, and was using a ruler to measure architectural sketches on the pages, her pen rapidly recording something in her notebook.
"What have you found?" Kyogumichi pulled out a chair and sat down. The coffee on the table was still steaming, clearly freshly made.
Chitanda Eru pushed a yellowed copy of "History of Sobu University Campus Architecture" towards him, her fingertip pointing to a page: "Look here, the record of the school building expansion in Showa 56 mentions that the basement of the old school building's west wing was originally built as an air-raid shelter. Later, due to water seepage issues, it was sealed off in the early Heisei period, but the architectural blueprints indicate three emergency exits."
Kyogumichi leaned in to examine it. The blueprint was hand-drawn, and the lines were somewhat blurry, but he could clearly see the structure of the basement—arranged in a '回' (hui, meaning 'return' or 'circle') shape, with a central area marked as 'Special Storage Room'. The three exits led to the old school building's boiler room, the west wing's stairwell, and... the Drama Club's prop warehouse.
"The Drama Club's prop warehouse actually has an entrance to the basement?" Kyogumichi frowned. "When we went to the Drama Club yesterday, we didn't see any trace of a passage."
"Because it was sealed off," Chitanda Eru said, opening another book, "Compilation of Club Activity Logs." "The record from Heisei 22 states that the Drama Club's prop warehouse underwent a renovation. At that time, to expand storage space, the door that originally led to the basement was bricked up, and a false wall was built over it."
She quickly sketched the warehouse's floor plan in her notebook with a pencil, drawing a box in the corner: "Based on the scale, the false wall should be behind the pile of miscellaneous items at the very back of the warehouse, about two meters wide."
Kyogumichi's fingertip traced the 'Special Storage Room' mark on the blueprint. This area was circled in red on the diagram, with a small note next to it: "Constant temperature and humidity, key kept by the Principal's Office."
"A storage room with constant temperature and humidity?" He raised an eyebrow. "An air-raid shelter wouldn't need this kind of design. Something must be hidden here."
Chitanda Eru suddenly remembered something. She rummaged through her backpack for her cousin's letters and spread the third letter on the table: "Look at this sentence, 'The eye behind the mirror is blinking.' There is indeed a full-length mirror in the Drama Club's prop warehouse, placed right next to the pile of miscellaneous items!"
Kyogumichi's gaze fell on the letter, then he looked up at the architectural blueprint, suddenly realizing something: "Behind the false wall is a passage, at the end of the passage is the storage room, and there's a mirror in the storage room... These three should be connected."
He pulled out his phone from his pocket and brought up the photo of the notebook he took last night—in that ten-year-old Drama Club group photo, Chitanda Nao, wearing a fox mask, was standing in front of the full-length mirror in the prop warehouse. The reflection in the mirror seemed a bit darker than the actual scene.
"There might have been a mechanism hidden in the mirror at that time," Kyogumichi said, zooming in on the photo. "Look at the reflection on the edge of the mirror; there's a very small protrusion, like a knob."
Chitanda Eru leaned closer to the screen, her breathing involuntarily quickening: "Then should we go to the Drama Club now?"
"Wait a minute," Kyogumichi said, holding her shoulder and pointing to the note on the last page of the architectural history, "It says here that the basement's power supply system was completely cut off in September of Heisei 23, and due to water seepage, some areas have accumulated very deep water."
He looked out the window. The setting sun was falling through the gaps in the ginkgo leaves, and golden light particles floated in the air: "It's too dangerous to go now. There's no light, and we don't know how deep the accumulated water is. We need to prepare flashlights, ropes, and waterproof equipment."
Chitanda Eru nodded vigorously, took out sticky notes from her backpack, and began making a list: "I have waterproof flashlights at home, and I can also bring some candles as backup. As for ropes, the school's mountaineering club should have some to borrow."
"We also need to check the campus incident records from Heisei 23," Kyogumichi said, getting up and walking towards the deeper part of the bookshelf. "Since Yoshida-sensei is hiding something, there might be clues in the school newspaper or student council records from that year."
The library's archive section was in the basement, and the air was colder than upstairs. Kyogumichi crouched in front of the metal cabinet labeled "Heisei 23" and pulled out the bottom box of files. The cover of the file was faded, and opening it stirred up a fine dust. Inside were bound compilations of the school newspaper.
He flipped through page by page, his fingertip tracing titles like "Culture Festival Special Issue" and "Sports Day Report," until he reached the middle of the September issue, where he found traces of a cut-out article. The remaining title only had the words "West Wing Sudden...".
"Someone deliberately cut it out," Kyogumichi said, handing the compilation to Chitanda Eru, who had walked over. "It seems someone doesn't want this part of history to be brought up."
Chitanda Eru's finger lightly brushed over the cut mark, and she suddenly noticed faint imprints on the back of the paper, as if stained with ink. She held the school newspaper up to the light and could vaguely make out the words "...Drama Club...accident...".
"It was an accident," her voice trembled slightly. "On the day of the courage test ten years ago, an accident must have happened in the basement."
Kyogumichi didn't speak, but simply pulled out another student council meeting record from the files. In the record for September 15th, there was an approval comment written in red pen: "Regarding the application for repair of the West Wing basement drainage system, postpone implementation. —Principal Sato."
"Postpone implementation?" Kyogumichi frowned. "If an accident really happened, it should be repaired immediately. Why postpone it?"
Chitanda Eru suddenly remembered her cousin's words and took out her phone to compare: "'Don't trust the person wearing the fox mask.' Could the principal at that time have been involved with the Drama Club?"
She quickly ran back to the bookshelves upstairs and soon returned with a copy of "Sobu University Past and Present Faculty Directory." She flipped to the Heisei 23 page: "Found it! The principal at that time, Sato Takeshi, graduated from the drama department and also served as the Drama Club's advisor!"
The clues, like scattered beads, were finally strung together—Principal Sato used his authority to conceal the basement accident, members of the Drama Club were involved, and Chitanda Nao's transfer and illness might all be related to this.
Kyogumichi closed the files and glanced at the darkening sky outside the window: "Let's prepare our equipment tonight. Tomorrow afternoon, during club activity time, the Drama Club will be empty, and we'll go then."
Chitanda Eru organized all the materials and put them into an archive bag, her fingertips slightly white from gripping it tightly: "My cousin's illness... it must be related to this."
"Once we find what's in the storage room, we might know the answer," Kyogumichi's voice was calm, yet carried a reassuring strength. "But we must be prepared; there might be things in there we can't imagine."
Chitanda Eru nodded vigorously, hugging the archive bag tightly. The last rays of the setting sun passed through the stained-glass window, casting blue-purple light spots on her face, her eyes filled with both tension and an undeniable anticipation.
Tomorrow would be a crucial step in uncovering the truth.