  We report on the detection and follow-up multi-wavelength observations of the
new X-ray transient MAXI J1807+132 with the MAXI/GSC, Swift, and ground-based
optical telescopes. The source was first recognized with the MAXI/GSC on 2017
March 13. About a week later, it reached the maximum intensity ($\sim$10 mCrab
in 2-10 keV), and then gradually faded in $\sim$10 days by more than one order
of magnitude. Time-averaged Swift/XRT spectra in the decaying phase can be
described by a blackbody with a relatively low temperature (0.1-0.5 keV), plus
a hard power-law component with a photon index of $\sim$2. These spectral
properties are similar to those of neutron star low-mass X-ray binaries (LMXBs)
in their dim periods. The blackbody temperature and the radius of the emission
region varied in a complex manner as the source became dimmer. The source was
detected in the optical wavelength on March 27-31 as well. The optical flux
decreased monotonically as the X-ray flux decayed. The correlation between the
X-ray and optical fluxes is found to be consistent with those of known neutron
star LMXBs, supporting the idea that the source is likely to be a transient
neutron star LMXB.
