The key to refining chakra was the power of the mind, not willpower. Keiko explained her understanding of chakra and, after teaching Mirai the Yamanaka clan's secret chakra extraction technique, pointed out, "Physical strength and mental energy continue to exist within our bodies, but we need our will to use them and turn them into chakra."
After listening to Keiko's detailed and clear explanation, Mirai's initially vague impression of the mysterious chakra gradually became much clearer.
"Aunt Keiko, shall we try refining chakra? Is there anything else I need to keep in mind?" Mirai could barely wait, asking as soon as Keiko finished speaking.
Keiko warned him that he could begin, but he had to remember that the first step in extracting chakra was to start with a part of the body he knew well, where he could achieve more. "And chakra refinement requires both utmost caution and absolute focus. Calm down, concentrate on your body, and use your will to feel it."
After carefully considering Keiko's advice, Mirai realized that his state of mind was wrong. He took a deep breath, sat cross-legged, and softened his breathing, gradually calming down.
As for which body part to choose first, Mirai decisively chose his right arm—the arm he had relentlessly trained as a twenty-year-old young man.
Mirai believed that although he now had a new body, the will of that arm had already been deeply imprinted on his soul. Its strength and his familiarity with it would never disappear simply because his body had changed.
Setting aside his thoughts, he held his breath and repeatedly recalled the chakra extraction technique Keiko had taught him.
The key to refining chakra was mental strength. In this regard, Mirai was undoubtedly among the greatest in the entire ninja world, so the refinement technique Keiko