We present the galaxy luminosity functions ( LFs ) of four Hickson Compact Groups using image data from the Subaru Hyper Suprime-Cam .
A distinct dip appeared in the faint-ends of all the LFs at M _ { g } \sim - 12 .
A similar dip was observed in the LFs of the galaxy clusters Coma and Centaurus .
However , LFs in the Virgo , Hydra , and the field had flatter slopes and no dips .
As the relative velocities among galaxies are lower in compact groups than in clusters , the effect of galaxy-galaxy interactions would be more significant in compact groups .
The M _ { g } \sim - 12 dip of compact groups may imply that frequent galaxy-galaxy interactions would affect the evolution of galaxies , and the dip in LF could become a boundary between different galaxy populations .