Board Thread:Theories and Speculation/@comment-26909463-20191217165935/@comment-38812954-20191220014810

chakra when it's not released at a high or good concentration, or to take form is invisible (well not to the sharingan and byakugan and rinnegan even).

for example. medic ninjutsu and kabuto's offensive medic ninjutsu. these are released at good concentrations, and as you said the rasengan; chakra released at good concentration to take form, following very fine tuning steps though.