  The Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) is used in a
search for single neutron or two neutron intra-nuclear disappearance that would
produce holes in the $\it{s}$-shell energy level of $^{12}$C nuclei. Such holes
could be created as a result of nucleon decay into invisible modes ($inv$),
e.g. $n \to 3\nu$ or $nn \to 2\nu$. The de-excitation of the corresponding
daughter nucleus results in a sequence of space and time correlated events
observable in the liquid scintillator detector. We report on new limits for
one- and two-neutron disappearance: $\tau(n\to inv)> 5.8\times 10^{29}$ years
and $\tau (nn \to inv)> 1.4 \times 10^{30}$ years at 90% CL. These results
represent an improvement of factors of $\sim$3 and $>10^4$ over previous
experiments.
