The Tale of Derek and the Hidden Sand Chapter 29

"To condense chakra normally, one needs to feel the spiritual and physical energy of the body and condense it into one's own body, but this is only the first step!"

Jiraiya said solemnly, "Each of the 361 acupoints in the human body can store a large amount of chakra."

"However, at the beginning of condensation, people can only open a small part of the acupoints, so as to store the chakra that has been successfully condensed in the early stage. In the future, each time condensation is carried out, the chakra will be stored in these acupoints first."

"But if this continues, those unused chakra points will become increasingly fragile and no longer able to withstand the powerful chakra energy. The chakra limit of a ninja will be fixed!"

"Therefore, in some real ninja families, when the chakra is just beginning to condense, they will not rush to ask their children to learn the ninjutsu of seal solidification."