  The bond-dependent Kitaev interaction $K$ is familiar in the effective spin
model of transition metal compounds with octahedral ligands. In this work, we
find a peculiar non-coplanar magnetic order can be formed with the help of $K$
and next-nearest neighbor Heisenberg coupling $J_2$ on the triangular lattice.
It can be seen as a miniature version of skyrmion crystal, since it has nine
spins and an integer topological number in a magnetic unit cell. The magnon
excitations in such an order are studied by the linear spin-wave theory. Of
note is that the change in the relative size of $J_2$ and $K$ produces
topological magnon phase transitions although the topological number remains
unchanged. We also calculated the experimentally observable thermal Hall
conductivity, and found that the signs of thermal Hall conductivity will change
with topological phase transitions or temperature changes in certain regions.
