  We present optical and near-infrared (NIR) observations of the Type Icn
supernova (SN Icn) 2022ann, the fifth member of its newly identified class of
SNe. Its early optical spectra are dominated by narrow carbon and oxygen
P-Cygni features with absorption velocities of 800 km/s; slower than other SNe
Icn and indicative of interaction with a dense, H/He-poor circumstellar medium
(CSM) that is outflowing slower than a typical Wolf-Rayet wind velocity of
$>$1000 km/s. We identify helium in NIR spectra obtained two weeks after
maximum and in optical spectra at three weeks, demonstrating that the CSM is
not fully devoid of helium. We never detect broad spectral features from SN
ejecta, including in spectra extending to the nebular phase, a unique
characteristic among SNe~Icn. Compared to other SNe Icn, SN 2022ann has a low
luminosity, with a peak o-band absolute magnitude of -17.7, and evolves slowly.
We model the bolometric light curve and find it is well-described by 1.7 M_Sun
of SN ejecta interacting with 0.2 M_sun of CSM. We place an upper limit of 0.04
M_Sun of Ni56 synthesized in the explosion. The host galaxy is a dwarf galaxy
with a stellar mass of 10^7.34 M_Sun (implied metallicity of log(Z/Z_Sun)
$\approx$ 0.10) and integrated star-formation rate of log(SFR) = -2.20
M_sun/yr; both lower than 97\% of the galaxies observed to produce
core-collapse supernovae, although consistent with star-forming galaxies on the
galaxy Main Sequence. The low CSM velocity, nickel and ejecta masses, and
likely low-metallicity environment disfavour a single Wolf-Rayet progenitor
star. Instead, a binary companion star is likely required to adequately strip
the progenitor before explosion and produce a low-velocity outflow. The low CSM
velocity may be indicative of the outer Lagrangian points in the stellar binary
progenitor, rather than from the escape velocity of a single Wolf-Rayet-like
massive star.
