Yan reached the practice alcove before dawn. The stone weight sat on a folded mat, wedged in place by two short boards. Gu had set the corrected Ashen Marrow pattern on the table and left the book locked in the cabinet.
“Three measured breaths,” Gu said.
“Not three full turns.”
“Where does the force release?”
“Out through the shoulder, away from the spine.”
Gu checked the answer against the page. His hand shook slightly as he turned it, but he steadied his wrist before setting the paper down. “The target is fixed. If it moves, stop. If you lose the count, stop. I can call the breaths, but you have to choose to release.”
Yan stepped onto the clean patch they had swept. He checked the mat and the wedges, then looked at the stone. “I understand.”
“Say what you understand.”
“The text warns that the third full circulation can destroy marrow. A small charge lowers the risk, but it does not make the method safe. This is one full circulation at low charge. I will follow the count and stop if I lose the route.”
Gu looked at him carefully. “Do you still choose to begin?”
“Yes.”
Yan set his feet and took one slow breath. Gu watched his shoulders and the line of his spine. Yan gathered a small charge below his navel. The qi rose across his chest, then turned toward his shoulder on the first measured breath.
“One,” Gu said.
Yan kept the force contained. It was warmer than his earlier circulation, dense and focused, but not painful. He followed the second breath along the marked route, letting it gather behind the shoulder instead of pushing toward his spine.
“Two.”
At the third breath, he released.
The force snapped through his arm and struck the stone weight. A sharp crack rang through the alcove. The weight split down one side and slid across the mat, stopping against the wooden wedge.
Yan’s arm recoiled. Beneath the skin, the pressure that should have crushed the marrow became a deep, steady warmth. It moved through the bones in his forearms and shoulders, settling them into a firmer line. His joints felt stable. The force had not weakened him; it had strengthened the frame that carried it.
A silent notice appeared in his mind.
Ashen Marrow strain reversed. Marrow strengthened; bone density increased.
Yan opened and closed his hands. His fingers moved freely. He rolled his shoulders, then bent his wrists in both directions. The internal warmth felt solid and pleasant, as if his bones had been set more firmly in place. The expected strain had not begun. No pain followed it.
He grinned. “Can I try another while the result is clear?”
Gu watched him rather than the stone. “Do not assume one result proves the next is safe.”
“I want to use the same low charge and the same count.”
“You have the right to choose. I will watch your pulse and the target.” Gu took Yan’s wrist. “First, let me check you.”
Yan held still. Gu counted the beats, then asked him to lift both arms and make a fist. Yan did. There was no tremor or numbness. Gu asked him to press his palms together, then separate them. The joints moved cleanly.
“What do you feel inside?”
“Warmth through the marrow. My bones feel firmer, not strained.” Yan hesitated, then added, “A silent notice called it strengthened marrow and increased bone density.”
Gu’s eyebrows rose. “You’ve seen notices before?”
“Yes. After the draught and the pills. I have not told anyone else until now.”
“What do they say?”
“They name the change. They don’t explain where the change comes from, and they don’t tell me what to do.”
Gu looked again at the split weight. “I expected the art to injure you. Your pulse is clean.”
“I know what the warning says.”
“I’m not telling you it is safe for everyone.”
“I wouldn’t ask you to.”
Gu marked the pulse and time in his notebook. The ink line stayed level. “The external force is exactly where the text said it would be. Your body’s response is the part I don’t understand.”
Yan looked down at his arms. The circulation had left no ache in the bones. “I can tell you what I felt. You can record what you measured.”
“That is enough for this morning.” Gu glanced at the target. “If you still want a second circulation, we keep the charge just as low.”
Yan had wanted to repeat the strike while the warmth remained. He had no reason to increase the force. “Same charge. Same route.”
He reset his stance. The sequence came naturally once he began. He counted each breath without Gu prompting him. At the release point, the force traveled through his shoulder and arm and struck the stone again.
The split deepened. A smaller piece broke free and clattered against the mat. Yan kept his footing. His bones accepted the strain as warmth, and his fist stopped where he had aimed it. He felt no drain or delayed collapse.
Gu marked the time and the target’s condition. “That was cleaner.”
Yan glanced at the first crack. “Was the weight already cracked?”
Gu lifted the largest section and turned it over. An old seam ran along the far side, mostly hidden by dust. He brushed it with his thumb, then checked the first break. The new fracture followed part of the old seam before splitting away.
Yan pointed at it. “The target was dishonest.”
“The stone still lost.”
“Then the method is excellent.”
“The target was compromised,” Gu said. “That is why we record what happened instead of declaring a winner.”
Yan laughed. “The stone can argue with you.”
Gu set it down carefully. “The stone has already made its point.”
He checked Yan’s pulse once more and watched him bend his wrists. The readings remained clean, but Gu did not call the technique safe. He asked Yan to wait, breathe normally, and report if any weakness or ache appeared. Yan did so while they packed the pieces of stone back onto the mat.
No weakness came. The warmth settled deeper in his bones without turning painful. Yan wrote the count, charge, strike direction, pulse, and target condition into a fresh record. He marked that the first weight had an old seam and that the second circulation deepened the fracture. Gu read over the entry, then added his own measurements.
For the first time, Yan knew that a warning about intrinsic cultivation damage could describe a benefit for him while remaining a real warning for everyone else. The external force had not changed. The stone had cracked exactly where the strike landed. His body had changed the part of the method meant to harm it.
Gu closed the notebook. “That is enough for today.”
Yan flexed his fingers and looked at the split weight. “Enough to start.”
“Enough to stop.”
Yan nodded. The marrow warmth remained steady. He had completed two low-charge circulations without a life drain, delayed collapse, or lingering pain. He would record the result before deciding what came next. The target’s old seam made the measurement less clean, but it did not erase the force in his arms.