On the first day of summer vacation, at five-thirty in the morning, Kanzaki Toru was awakened by his phone vibrating. It was not a notification from the academic affairs system, but a scheduled message signed "&," arriving to the very second. This time, the content was shorter than ever, only a single line: "The final missing chapter of the Uninhabited Island ecological data report has been shelved in the Library's summer open-day archives. ID: LD-SUMMER-0001. &." He finished reading the message and sat up in bed. Pale golden morning light seeped through the gap in the curtains. Above the high walls, the sky was a pure light blue without a trace of impurity. The cicadas had yet to begin calling, but the air already carried the distinctive scent of hot grass and leaves in high summer.
The Library's summer open day was scheduled for nine in the morning. It was one of Advanced Nurturing High School's rare lenient policies—during summer vacation, the Library opened for three hours every Monday, Wednesday, and Friday morning, allowing students to freely consult non-examination archives. But IDs beginning with LD did not belong to examination materials; they were prefixes reserved for archived experimental data from the Old System. After washing up and changing into his uniform—though the school did not require uniforms during summer vacation, he had grown accustomed to the weight of the white shirt, much like Shiina Hiyori was accustomed to hanging her key ring from the left side of her waist, and Karuizawa was accustomed to stuffing a can of red bean soup into her bag. Habits were among the few constants in this school surrounded by high walls that the school's rules could not alter.
The campus was nearly deserted on the first day of summer vacation. A few students were