The Price of Devouring

Senju Shinichi had a fever.

Not the kind of low fever you got from kicking off the covers and catching a chill the night before. This was a high fever that made his whole body shake, his teeth chatter, and soaked even his pillow with sweat. Even wrapped in three layers of blankets, he still felt cold. It was as though ice water had been poured into the gaps between his bones, then red-hot irons stuffed in after it, the cold and heat taking turns without the slightest regard for reason.

The matron discovered it that morning. As usual, she pounded on the door and shouted that breakfast was ready. After getting no response three times, she pushed the door open and found Shinichi curled into a ball on the bed, his face an unnatural red and his cracked lips pale. The moment she touched his forehead, her hand jerked back as though she had been burned.

"Go get a medical ninja!" she roared at Little Fatty behind her. Startled, Little Fatty dropped the bun in his hand and ran downstairs.

Half-conscious, Shinichi heard the matron shouting and wanted to speak, but his throat was as dry as sandpaper. He could not force out a single word. His awareness drifted back and forth between clarity and delirium. Sometimes, he could feel someone placing a cold towel over his forehead. Other times, he sank completely into a chaotic darkness.

In that darkness, he heard the system speaking.

No, it was not speaking. It was stuffing information into his mind, one line at a time, cold and devoid of emotion. Like a machine in a hospital printing test results, indifferent whether the paper said "normal" or "malignant."

"Rejection response initiated. Cause: Host has devoured foreign chakra for the first time. The Senju Clan bloodline is rejecting Wind-nature chakra. Estimated duration: 24 to 48 hours. Recommendation: Drink plenty of water, maintain body temperature, no special treatment required."

In the haze, Shinichi read through the message once, then cursed silently with the last shred of clarity he had.

That had never been written in the manual.

No, that was wrong. It had.

"Restriction: Fusing with high-level bloodlines will be accompanied by intense pain and carries the risk of bodily explosion."

When he had said "got it," he had been thinking about the day he devoured impressive things like First Hokage cells, Sharingan, or Tailed Beast chakra. He had never imagined that devouring an ordinary Wind-nature chunin for the first time would trigger rejection. When he finished reading the manual back then, he had felt like a user clicking "I have read and agree to the terms of service" without reading a single word. Now the system was coldly telling him: sorry, there was no trial version. Even if he had only devoured a tiny bit, he still had to go through the proper process.

Wind nature.

The Senju Clan bloodline had Earth and Water natures. Adding Wind all of a sudden was like someone pouring half a cup of ice-cold beer into the cup of a health-conscious person who had spent years drinking only warm water. His body had not adjusted in time. His immune system immediately sounded a top-level alarm, his chakra pathways went into full lockdown, and every defensive mechanism activated at once, treating the foreign chakra as an invader and attacking it with everything it had. The battlefield was Shinichi's blood vessels and chakra pathways.

He turned over and buried his face in the pillow. The pillow was wet. He did not know whether it was sweat or drool from last night. Either way, it did not matter anymore.

When the matron came in with the medical ninja, they found a six-year-old child curled up like a shrimp, his face flushed, his breathing rapid, and the veins on his forehead faintly bulging. He looked frightening, but Shinichi knew this was only the surface.

What truly made him suffer was not the fever, but the pain. Every muscle in his body ached. Not the kind of soreness after exercise, but the kind that felt like someone had twisted him like a towel all night before spreading him back out. His bones were alternately cold and hot, and his chakra pathways felt as though they were breakdancing. The sensation was hard to describe. If he had to make an analogy—it was like every cell in his body was holding a massive internal audit meeting. The subject being audited was the newly arrived Wind-nature chakra, and the conclusion was: "Origin unknown. Approval denied. Deport immediately."

Then the deportation failed. The Wind-nature chakra refused to leave. The cells began a sit-in protest. That was the principle behind a fever.

Shinichi had already drafted an entire "cell union strike" script in his head, complete with slogans and banners, before his consciousness sank again. When he woke up next, there was someone beside his bed.

It was not the matron.

It was the medical ninja.

She was a young woman in her early twenties, wearing round-framed glasses and a neatly washed green medical ninja robe. One hand, glowing with a faint green light, hovered over Shinichi's chest as she closed her eyes and sensed the flow of chakra. Her brows were slightly furrowed, and she looked utterly confused.

"Strange," she muttered. "Why is the chakra inside this child fighting itself?"

Half-conscious, Shinichi nearly laughed when he heard that. No, he did laugh. The corners of his mouth lifted. That description was too accurate. A cell union strike was not enough—the chakra itself had entered the fray and started a brawl. His little body had stolen something from someone else and was now in the middle of a civil war.

Fortunately, the system had not lied to him. The rejection response faded after around thirty hours. When Shinichi opened his eyes on the morning of the third day, the fever had already broken. His body was still a little weak and sore, but his chakra pathways no longer hurt. The alternating cold and heat between his bones had also stopped. It felt as though his whole body had been reformatted. Clean, yes, but empty and weak.

He tried moving his fingers. They moved. Then he tried his toes. They moved too. He threw off the blankets, sat up, and looked out the window. The sunlight was perfect. Leaves on the old locust tree in the courtyard rustled in the wind, while Little Flower chased butterflies downstairs.

He had survived.

"Rejection response concluded. Host's body has fully adapted to foreign chakra. Current status: Stable. Fusion rate with Senju Clan bloodline: 100%. Chakra pathway adaptability: Significantly increased. Probability of rejection from devouring targets of the same level in the future: Greatly reduced."

Shinichi stared at the message in silence for a while.

"So the first time was the system forcibly teaching me a lesson."

He finished the thought in his head without waiting for an answer. He knew the system would not answer. The system was not a teacher. It would not review the lesson with him afterward. It was more like a law of physics in this cruel world—if you did something with a price, then that price would inevitably come due. It was not responsible for soothing his feelings. It was only responsible for enforcing the rules.

Every time he fused with a new bloodline in the future, he would have to consider the cost.

Still, although those thirty hours had been hard to endure, he noticed one detail: his chakra reserves had increased. Not by much, perhaps twenty to thirty percent. He had practiced tree climbing for so long, yet his progress had been about the height of a finger. Now, after devouring part of an ordinary chunin's chakra, his reserves had risen by nearly thirty percent.

At last, he understood the system's growth logic. Training could take you from one to ten, but devouring could take you from one to a hundred. The only problem was the hurdle of a raging fever in between.

Sitting on the bed, he slowly worked his wrists and ankles while already planning his next move. Once his strength returned, he needed to double his training. The rejection response had been agonizing, but after surviving it, his body's resilience had clearly improved—like a rubber band that had snapped once and, after healing, could stretch farther. The analogy was not very scientific, but he had studied computers. Comparing the human body to a rubber band had already exhausted all his biological knowledge.

Footsteps sounded outside, followed by the door opening. The matron walked in carrying a bowl of hot porridge. Seeing a living person sitting up in bed and blinking, she froze for a moment. Then her expression changed from worry to relief, and from relief to her usual fierce scowl.

"If you sneak out in the middle of the night to catch cold again, I'll make you sleep in the kitchen."

"Yes, Matron." Shinichi nodded obediently.

"Drink the porridge."

"Yes, Matron."

"Lie down and don't move after you finish."

"Yes, Matron."

The matron narrowed her eyes at him, probably wondering why this child was agreeing so quickly and whether he was plotting something again. But she had already brought the porridge, and she could hardly take it back, so she shoved the bowl into Shinichi's hands and checked the thickness of his blankets before leaving.

Shinichi slowly drank the porridge. It was plain rice porridge with a few strands of egg floating on top and some salt added. The matron only added egg when someone was sick. It was an unspoken rule at the orphanage. Over the past six years, he had eaten egg-drop porridge many times, every time because of a fever. But he knew there would not be fewer fevers in the future. Every devouring might bring one, and the scale and intensity were uncertain. The matron had probably made this bowl of porridge in the kitchen while grumbling under her breath. Her mouth was harsh, but she had added more than twice as much egg as usual.

After finishing the porridge, he lay back down and began calculating again. The Root chunin who had fainted in the forest had definitely been taken back already. With Danzo's methods, finding out that someone had been operating outside the village and had even gotten close to a transport route would not be brushed aside so easily. He had better behave himself over the next few days and stop going outside the village.

Perfect. He needed time to digest the gains from this devouring.

The Wind-nature chakra had brought him not only a new nature, but also basic throwing skills with ninja tools. It was a subtle feeling—there was something extra in his mind, but not in the form of knowledge. It was more like muscle memory. He knew at what angle a shuriken needed to be thrown for it to spin along the best trajectory. He knew how much force a kunai needed at the instant of release to hit precisely. Like someone who had learned how to swim—after staying out of the water for years, their body would still automatically assume the right posture.

What he needed to do now was truly integrate that muscle memory with this six-year-old body. It was not enough to merely know how. He needed to practice until he could do it without thinking. Even if he only trained one thing, he had to train it to a level that could save his life.

He slept another two hours that afternoon and felt much better when he woke. While the other children were out playing, he pulled the kunai from beneath his pillow and found an old locust tree in the backyard to use as a target.

The first throw missed, embedding itself in the ground half a meter beside the trunk. After all, even muscle memory needed time to adjust.

He bent down to pick up the kunai, returned to the throwing line, and repeatedly adjusted his angle and strength. The second throw grazed the bark. The third sank half an inch into the wood. By the tenth throw, it nearly struck the mark he had made earlier. Wind-nature chakra changed the airflow around the kunai as it left his hand. With a slight flick of his wrist, the Wind nature automatically extended along the kunai's edge to its tip, making it fly steadier and pierce deeper.

He stood before the tree for a long time, looking down at his hand. The rejection response had been a warning, telling him that power came with a price. It was an empty phrase. Anyone could say it. But truly understanding it came only after personally touching the boundary of that price, after being tortured by a high fever for thirty hours and still deciding to continue down this path. It was not "I understand." It was "I accept it."

He returned to his room and hid the kunai beneath his pillow again. The pillow was too small to conceal it properly. He would hide it under the bed boards instead. Tomorrow, he would buy a piece of cowhide and make himself a target.

At dinner, he ate three large bowls. Little Flower watched beside him, her mouth forming a round O.

"Your appetite's this good as soon as your fever breaks?" The matron came over carrying a pot of soup. When she saw him reaching for his fifth bun, her eyebrows nearly shot up into her hairline.

"Restoring my strength," he said indistinctly.

The matron set down the soup, looked at him for a while, then said something in the tone of someone speaking from experience that nearly made him choke. "Children shouldn't imitate adults by staying up late and running around at night. Konoha's nights aren't as safe as you think."

With a bun stuffed in his mouth, Shinichi nodded hard. His expression was as sincere as that of a model student.

But what he was thinking was—Matron, you're too late.

And he would keep doing it in the future.