  A negative ion micro time projection chamber (NI$\mu$TPC) was developed and
its performance studied. An NI$\mu$TPC is a novel technology that enables the
measurement of absolute $z$ coordinates for self-triggering TPCs. This
technology provides full-fiducialization analysis, which is not possible with
conventional gaseous TPCs, and is useful for directional dark matter searches
in terms of background rejection and the improvement of the angular resolution.
The developed NI$\mu$TPC prototype had a detection volume of 12.8 $\times$ 25.6
$\times$ 144 mm$^{3}$. The absolute $z$ coordinate was determined with a
location accuracy of 16 mm using minority carrieres of SF$_{5}^{-}$.
Simultaneously, there was a successful reconstruction of the three-dimensional
(3D) tracks with a spatial resolution of 130 $\mu\rm{m}$. This is the first
demonstration of 3D tracking with the detection of absolute $z$ coordinates,
and it is an important step in improving the sensitivity of directional dark
matter searches.
