Lunar Terahertz Surveyor for Kilometer-scale Mapping (TSUKIMI), a collaborative mission for lunar exploration, is introduced. We numerically explore terahertz scattering and emission from the lunar surface as an initial step forward. Regarding the characterization of the lunar surface, the power-law spectrum is adopted to model the roughness. While for the dielectric constant of the lunar surface, tentatively simplifying into a homogeneous condition. The scattering and emission models are briefly described. To investigate the terahertz scattering effect from the lunar surface, we conducted the preliminary experiments with dielectric constant and surface roughness using THz- TDS and T-Ray 4000 Picometric, respectively. The measurement results are subsequently presented.