Remarkable enhancements of the thermospheric mass density around the 400-km altitude in the cusp region have been observed by the CHAllenging Minisatellite Payload (CHAMP) satellite. We employed a high-resolution two-dimensional local model to gain insights into the extent to which the neutral-ion drag process controls the mass density’s enhancements under the energy inputs typical of the cusp. We expressed those energy inputs by quasi-static electric fields and electron precipitation. We compared two cases and calculated the thermospheric dynamics with and without neutral-ion drags. We found that in the more realistic case containing the neutral-ion drag, the calculated mass density enhancement was 10% at most, which is dramatically smaller than the observations by the CHAMP satellite (33% on average). The results also showed that the neutral-ion drag process suppresses Joule heating and neutral mass density enhancements, as well as the chemical reaction process. The discrepancy between our modeling result and the satellite observation suggests the existence of additional energy sources, such as Alfvén waves propagating from the magnetosphere, which play an important role in the cusp’s density enhancement.