Chen Hao leaned against the rock wall, his fingers picking at a clump of dry moss in a crevice. The green moss had long since turned grayish-white from the sun and crumbled into powder at the slightest touch. He stared at the remnant in his palm for two seconds, and suddenly felt that this thing was exactly like his last hope.

Nana stood to the side, her mechanical eyes scanning the sky. She didn't speak, but a slight hum emanated from the heat vents on her shoulders, a signal that the system was operating at full speed.

"Do you think... there's still hope?" Chen Hao flicked away the ashes and clapped his hands.

“Yes,” she said. “It will rain in three hours.”

He was taken aback. "Are you serious?"

"Atmospheric humidity is rising, southwest winds are carrying water vapor, and cloud density matches the characteristics of cumulonimbus clouds. The probability of rainfall is 89.6%."

“No, I’m not asking about the data.” He sat down, leaning against the stone. “I’m asking, can this land come back to life?”

Nana glanced down at him, fine-tuning the focus of the optical lens. "Currently, the vegetation survival rate is 0.3%, and the soil moisture content is below the absorption threshold of plant roots. The food chain has been broken."

“Then it’s hopeless.” He looked up at the sky, squinting. “But why are you still forecasting rain?”

“Because natural systems are not equivalent to human expectations,” she said. “They simply operate according to their own laws. Rain will fall, but that doesn’t mean everything will return to normal.”

"Hey, that's so depressing," he grinned. "But I like hearing it."

The two fell silent. The wind swept through the ravine, stirring up a layer of loose soil, which swirled in the air before settling down. The thin stream in the distance was still flowing, creeping along the trench they had dug themselves, as if trying to avoid being discovered, hugging the ground.

Chen Hao suddenly stood up, staggered a few steps, and walked to the edge of the field. There was only a patch of scorched, yellowed stalks left; the drought-resistant grass seeds he had planted had vanished without a trace. He squatted down, reached out and picked up a broken stem, gently pinching it until it crumbled into dust.

The moment his fingertips left, a small seedling that was barely holding on swayed, its only leaf slowly curled up, its color changing from green to brown, and finally fell to the ground with a thud, turning into dust.

He didn't move or make a sound.

After a few seconds, he whispered, "The last green leaf is dead."

Nana walked over and stood half a step behind him. "But the timing of its death is crucial," she said. "It died just as the weather conditions turned favorable. This shows that extreme environments suppress life until the very last moment."

"So we have to hold on until the very last moment?" He turned to look at her.

“No,” she said, “I’ve already made it this far.”

He laughed, a little breathless. "Then I'll start preparing the celebration banquet menu now. The first dish is mud stewed with pebbles, limited quantity available."

"I suggest adding a moisture testing step," she said calmly, "to prevent accidental ingestion of highly saline and alkaline precipitates."

"You are such a romantic partner."

They returned to their hideout, where the drilling rig was still under the rubble, a wisp of heat rising from the ventilation cracks. Chen Hao slumped to the ground, took off his shoes, and poured out a handful of sand. "We're like underground workers now," he said, "we have to sneak around even to get water."

“Survival is all about stealth,” she said, activating the backup power and enhancing the weather tracking module. A semi-transparent projection appeared in the air, showing a dark gray cloud slowly gathering, its edges gleaming with a metallic sheen.

"These clouds... don't look very friendly." He frowned.

“This is not a typical monsoon system,” she said. “It has unusual energy characteristics and may be accompanied by strong ionization.”

"What do you mean? A lot of thunder?"

"Possibly."

"Who cares?" He lay down, putting his hands behind his head. "We don't have an umbrella anyway, so let's just get soaked."

The rain came sooner than expected.

The first drop hit his forehead, sending a shiver down his spine. He opened his eyes abruptly and saw a crack appear in the gray sky, followed by a second, a third... sparse raindrops began to fall on his face, hands, and clothes.

He slowly sat up, reached out and caught a drop, looked at it, and then licked it.

“Real water,” he murmured. “No saltiness, and no poison.”

The next second, he jumped up, spread his arms, and rushed into the rain, shouting with his head tilted back, "It's raining! It's really fucking raining!"

Rainwater streamed down his hair and into his neck, his soaked clothes clinging to his body. Instead of dodging, he rolled around in the mud, splashing water everywhere.

"I got a bath! Free full-body spa!" he yelled as he slapped the mud off his body. "I haven't had such a refreshing bath in three years!"

Nana remained standing in place, water droplets beginning to accumulate on her mechanical casing. Her sensors automatically switched to moisture-proof mode, and her optical eyes continued scanning for high-altitude clouds.

“Rainwater contains trace amounts of nitrates, which are beneficial for soil fertility,” she reported. “However, there are abnormal fluctuations in the electromagnetic environment.”

Chen Hao was burying his face in the puddle and taking a big gulp when he looked up and spat out a spray of water. "What?"

“High-intensity pulsed electromagnetic waves.” She raised her arm and pointed to the center of the clouds. “The frequency is not within the known communication spectrum, and it is periodic, repeating every seven seconds.”

"Oh." He wiped his face. "Was that an alien saying hello?"

“The source cannot be identified,” she said, “but the signal strength is sufficient to interfere with the operation of electronic devices. We recommend entering protective mode.”

"Protection?" He stood up, dripping wet, and grinned at her. "Do I look like I can protect myself? All I want to do right now is do ten somersaults in the rain!"

Before he finished speaking, he actually plunged headfirst into a mud puddle, rolled twice, got up, and continued jumping.

Nana's robotic arm suddenly stiffened, and her optical eye flashed red: "Warning, signal strength increased by 47%, intensifying in sync with precipitation. Signs of active modulation are present."

Just as she was about to continue her analysis, Chen Hao rushed over and pushed her down into the mud.

"Stop analyzing!" he yelled in the rain. "Get soaked first! If you keep talking about data, I'll throw you into the river for three days!"

Nana lay in the mud, her back sensor briefly malfunctioning but still intermittently recording: "Signal... stable cycle... suspected... remote control..."

Her voice was drowned out by the sound of the pouring rain and Chen Hao's shouts.

Chen Hao stood in the rain, his hands raised to the sky, rainwater streaming through his fingers. His eyes were closed, his face covered in water; it was impossible to tell if he was crying.

“We’re still alive,” he said. “The water’s come, the sky’s cleared, and I’m still alive.”

Nana pushed herself up from the mud, water dripping from her outer shell, the mechanical joints emitting a soft gurgling sound. She didn't respond, instead putting all non-essential modules into hibernation and concentrating her computing power to track the signal hidden in the thunderstorm.

It happens every seven seconds, so precise it seems like a natural phenomenon.

She pulled up the spectrum and tried to decode it, only to find that the signal structure was complex and contained nested encryption features. Even stranger, with each pulse burst, the rhythm of the raindrops hitting the ground would subtly change, as if the entire rainfall process was being controlled by some force.

“This is no coincidence,” she said softly.

Chen Hao was finally exhausted. He slumped down in the mud, hugging his knees and panting. The rain washed away the mud from his face, revealing his original skin color.

"You said... could it rain like this every day from now on?" He looked up at the sky. "It doesn't have to be heavy, just a light drizzle, enough to drink."

“No,” she said. “This level of rainfall won’t last more than four hours. After that, a new high-pressure system will take over.”

“I know,” he smiled. “I was just asking.”

He sat for a while longer, then suddenly asked, "Is that wave you mentioned still there?"

“Yes,” she nodded, “and it’s become clearer.”

"Did it come from the clouds?"

"The source is located at the core of the cloud layer, at an altitude of about 8,200 meters. Its movement speed is zero, and it is stationary relative to the ground."

"Hovering?" He frowned. "Whose satellite can stay still like that?"

“It’s not a satellite,” she said. “The signal pattern doesn’t match any known man-made platform.”

What is that?

She paused for a moment, her optical eyes narrowing slightly.

"I have no idea."

Chen Hao stared at her for a few seconds, then suddenly grinned and said, "You actually said you didn't know? That's impressive."

“I’ve said it many times,” she corrected, “but you usually choose to ignore it.”

“I didn’t ignore it this time.” He stood up and wiped his face. “This time I’m listening.”

The rain intensified, and the water in the ditches began to flow more rapidly, rushing down the slope. The once-dry depressions gradually filled with puddles, reflecting the leaden sky.

Chen Hao walked to the water intake and watched the water flow into the main canal they had dug. He squatted down, scooped up a handful of clear water, and examined it carefully.

“This water… is clean,” he said softly. “It can sustain life.”

"The prerequisite is that the ecosystem can be restarted," she said. "It requires seeds, time, and no more human destruction."

“We’ll hold it.” He sprinkled water, creating a ripple. “If anyone tries to take it again, I’ll have Nana arrange a free electrotherapy treatment for them.”

“The package details have been updated,” she said. “New addition: mandatory outdoor showers on rainy days.”

He laughed heartily, his laughter mingling with the sound of rain and carrying far.

Just then, Nana's robotic arm suddenly jolted.

“The signal suddenly changed.” She quickly pulled up the data. “The pulse frequency increased and the interval shortened to five seconds. At the same time, the charge distribution inside the cloud showed a directional shift.”

"What's the meaning?"

“It’s responding,” she said. “Someone or something is receiving our feedback.”

"Feedback? What did we do?"

“We used water,” she said. “And the water was a result of this rainfall. Perhaps… that was the trigger.”

Chen Hao's smile gradually faded.

He looked up at the sky; the rain was still falling, as dense as a curtain. But at that moment, he suddenly felt that the rain was no longer so gentle.

"You mean...it knows we got the water?"

"The probability is extremely high."

"So this wasn't natural rain?" His voice lowered. "It was... a test?"

Nana did not answer.

Her optical eye locked onto the high sky, recording the interaction between each pulse and the rain.

Raindrops fell on her face, sliding down the metal casing like tears.

Chen Hao stood beside her, soaking wet, without saying a word.

In the distance, water flows merrily towards the parched land.

Nearby, Nana's mechanical fingers tightened slightly, emitting a short buzzing sound.

That was the sign that she was in her highest alert mode.