The First Lesson of the Shared Pool

On the second morning on the uninhabited island, Kanzaki Toru was awakened by the final sweep of white light from the lighthouse. Morning light had just begun to spill over the horizon, and the June sea mist was sliced by the rising sun into a pale golden gauze, blanketing the shrubbery and the thin mountain spring on the back slope. The water filter in the communal pack had settled naturally overnight, leaving a faint layer of mineral sediment at the bottom of the bucket. Ishizaki was already crouched by the water source, using a folding shovel to widen the mud banks on either side by about a palm's width. His movements were at least twice as slow as when he had been hacking through vines the day before, but every strike of the shovel landed at a precise, consistent depth.

Morishita Ran's internal clock was sharper than any alarm; by the time Kanzaki stepped out of the tin shack, she was already sitting on her cot, organizing the communication logs. She projected the freshwater allocation spreadsheet submitted by each group onto the shack's only folding table, her finger tapping the six remarks in the final column of Group 12's sheet—each allocation was accompanied by a justification. "The school's backend has flagged our freshwater allocation notes as 'standard examples,'" she said, looking up at Kanzaki. Her expression was neutral, but her voice held a suppressed sense of surprise. "From this moment on, the shared pool weighting is being factored into our score. The arguments we had yesterday afternoon on the trail regarding map coordinates and equipment weight were also calculated into a 'collaboration friction coefficient'—since the value is below the threshold, our collaboration score has automatically been raised by one level."

Kanzaki took the tablet from her. The "Collaboration Score" field on the screen had turned green, accompanied by a line of small text: "Current Score: B+. Only one level away from unlocking the task supply crate." He returned the tablet to Morishita and turned to the shack entrance to relay the news to the rest of the group.

Hamaguchi was performing a third comparison on a water quality test strip; he merely nodded at the news and continued writing his notes. Nomura was re-tracing the signal attenuation circles on the paper map with a highlighter, casually adding a note next to the cliff coordinates: "High degree of weathering on the cliff face; suggest completing the climbing equipment wear-and-tear assessment before the fourth day." Shiina Hiyori was sitting on her cot, leafing through the Old System's shared pool appendix. Her light chestnut hair was still unbound, but she had already written out a complete set of key-node projections corresponding to the unlocking clauses and taped them above the iron lock of the supply crate. Yesterday, the lock had merely been scrutinized; today, its unlocking conditions were calculated down to every scoring tier—they were only one level away from opening the box.

At nine in the morning, the school sent the second day's task via satellite short message. The title consisted of only four characters: "Freshwater Crisis." Each group was required to complete two designated challenges within the day: first, to accurately measure the actual freshwater consumption of all six members over twenty-four hours and compare it to the estimated allocation plan submitted yesterday—an error margin exceeding twenty percent would result in a deduction of the collaboration score. Second, to locate at least one new source of potable water and conduct an on-site quality test, with data requiring confirmation by at least four members before submission. At the end of the task instructions was a line of red text: "The water resource allocation data collected for this task will be incorporated into the real-time weighting calculations for the Old System's shared pool clauses. Each group's submitted allocation justifications will be reviewed one by one by the school's backend; allocations with insufficient justifications will be automatically excluded from the shared pool by the system."

Kanzaki projected the task instructions onto the outer wall of the tin shack. The June sun crossed the shrubbery to shine on the rusted metal, the morning shadows casting the focused profiles of each member. Ishizaki put down his shovel and wiped his forehead with the back of his dirt-stained hand. He had hacked at the vines too aggressively yesterday, and his shoulders were still aching, but he didn't grit his teeth and stay silent like he used to at the gym. He simply leaned the shovel against a tree trunk and walked over to Kanzaki to look at the screen. "Freshwater consumption—we wrote an allocation reason for every bottle yesterday, but we didn't actually weigh the consumption one by one."

"The estimates were just numbers on paper before today; now the school wants us to reconcile them with real data." Kanzaki's gaze shifted from the red text to the wooden crate. "If the actual consumption error is below twenty percent, the collaboration score will rise to A-level, and the supply crate will unlock simultaneously. Morishita, you're in charge of recording each person's water intake; ensure the precision is reproducible. Nomura, mark the candidate coordinates for new water sources on the paper map. Hamaguchi and Ishizaki, form a water sampling team to check the coordinates one by one. Shiina, cross-reference the Old System clauses to confirm if the allocation justifications are compliant. I'll handle the final verification and submission."

The division of labor was concise and clear; everyone found the one thing they needed to focus on for the next four hours. There was no arguing, no repetitive confirmation. The dispute over map coordinates on the shrub-lined path yesterday was like a pebble pressed into the dirt, now quietly embedded in the rhythm of everyone's stride.

Ishizaki and Hamaguchi walked down along the back slope. Downstream from the mountain spring, there was a damp hollow obscured by ferns. Hamaguchi pushed the fronds aside and discovered a very shallow seepage layer at the bottom of the hollow. The water was clear but the flow was minimal; it took a long time to fill half a cup using a folding cup. Ishizaki crouched beside him, dipped the test strip into the cup, and read the indicators against the color chart. There was no unnecessary small talk between them, only the soft touch of the test strip against the water and the scratching sound of Hamaguchi's pen as he filled in the record sheet.

At ten-thirty in the morning, Kanzaki gathered everyone in the center of the camp to verify the comparison data between the first actual consumption and the estimated plan. Morishita read out the water intake records one by one—some had overestimated by nearly ten percent, while others had consumed less than expected between their two water-taking intervals. The final cumulative error was 6.7 percent, far below the twenty-percent red line set by the school. As she projected this data, the collaboration score on the terminal jumped—from B+ to A-. The seal on the wooden crate in the corner of the shack snapped, and the lock popped open automatically.

Inside the unlocked supply crate were three neatly arranged rows of equipment: a folding solar distiller, three spare water filters, a waterproof satellite weather map, and an envelope sealed with wax. Kanzaki opened the envelope to find a handwritten card, the script lean and forceful: "The shared pool is not an equal-distribution pool. Every resource in the pool stands on its justification. Allocations without reasons will automatically expire when you need your teammates the most. This test only covers freshwater; next time, it might not. Sakagami."

He read the words on the card to the group, sentence by sentence. Ishizaki crouched beside the supply crate, his fingers gently tracing the folding frame of the solar distiller—not with the frantic energy of grabbing a drainpipe while climbing a wall, but with the hesitation of someone having their bench press form corrected for the first time at the gym. He looked up at Morishita Ran, who was sitting on the cot opposite him, and asked, "Does Class A have a course called 'Fundamentals of Environmental Engineering'?" Morishita nodded. "Then you teach me how to use this, and I'll help you divert the water flow from the back slope."

Hamaguchi and Nomura had already begun comparing the satellite weather map to plan tomorrow's surveying route. Shiina picked up Sakagami's card and flipped it over—on the back was an even smaller line of text: "To Group 12—that path you wandered at the same coordinates last year, you didn't take it today." She tucked the card into the outermost layer of the Old System clause reference guide, showing it to no one, and simply added an "&" symbol to the remarks column of the shared pool weighting calculation sheet.

By dusk, all the sampling data for the new water sources had been verified. Kanzaki pressed the "Group Confirmation" button on the submission terminal, and a prompt popped up on the screen: "Task completion 100%, Collaboration Score A-, Shared pool weighting bonus now in effect." Outside the tin shack, Ishizaki and Morishita were crouched in front of the solar distiller, adjusting the angle of the mirror. The first drop of purified water from the distiller slid slowly into the collection bottle, merging with the mountain spring water in the same bucket. Hamaguchi wrote the final note of the day in the log: "Freshwater Crisis task concluded. New water source ID: NS-03. Water quality meets direct-drinking standards. Suggest re-checking for microbes before tomorrow's task begins. Recorder: Hamaguchi Tetsuya." The neat handwriting sat side-by-side on the folding table with the data sheet Ishizaki had filled out that morning.

Night mist rose from the sea once more, and the lighthouse's white light swept over the tin roof at a steady pace. Tomorrow's task title had not yet been released, but the water in the shared pool was filling the scale, drop by drop.