  Pre-stellar cores represent the initial conditions of star formation.
Although these initial conditions in nearby low-mass star-forming regions have
been investigated in detail, such initial conditions remain vastly unexplored
for massive star-forming regions. We report the detection of a cluster of
low-mass starless and pre-stellar core candidates in a massive star
protocluster forming cloud, NGC6334S. With the ALMA observations at a
$\sim$0.02 pc spatial resolution, we identified 17 low-mass starless core
candidates that do not show any evidence of protostellar activity. These
candidates present small velocity dispersions, high fractional abundances of
NH$_{2}$D, high NH$_{3}$ deuterium fractionations, and are completely dark in
the infrared wavelengths from 3.6 up to 70~$\mu$m. Turbulence is significantly
dissipated and the gas kinematics are dominated by thermal motions toward these
candidates. Nine out of the 17 cores are gravitationally bound, and therefore
are identified as pre-stellar core candidates. The embedded cores of NGC6334S
show a wide diversity in masses and evolutionary stages.
