Through mean-field calculations, we demonstrate that, in a large Z nucleus binding multiple muons, these heavy leptons localize within a few dozen femtometers of the nucleus. The mutual Coulomb interactions between the muons and protons can lead to a substantial decrease in proton chemical potential, surpassing 1 MeV. These findings imply that, in principle, the proton-dripline can be expanded on the nuclear chart, suggesting the possible production of nuclei with Z around 120.