  We study a topological superconductor island with spatially separated
Majorana modes coupled to multiple normal metal leads by single electron
tunneling in the Coulomb blockade regime. We show that low-temperature
transport in such Majorana island is carried by an emergent charge-$e$ boson
composed of a Majorana mode and an electron from the leads. This transmutation
from Fermi to Bose statistics has remarkable consequences. For noninteracting
leads, the system flows to a non-Fermi liquid fixed point, which is stable
against tunnel couplings anisotropy or detuning away from the charge-degeneracy
point. As a result, the system exhibits a universal conductance at zero
temperature, which is a fraction of the conductance quantum, and
low-temperature corrections with a universal power-law exponent. In addition,
we consider Majorana islands connected to interacting one-dimensional leads,
and find different stable fixed points near and far from the charge-degeneracy
point.
