[CII] luminosity function predicted by the G.A.S.+CLOUDY model from z = 4.0 to z = 7.6. The blue solid curve shows the prediction that accounts for the attenuation of [CII] emission due to the CMB. The blue dotted line would be the luminosity function ignoring the attenuation. At z ≃ 5, we show the observational constraints from Capak et al. (2015). At z ≃ 6, the black squares indicate the observational results of Yamaguchi et al. (2017). We also add the local [CII] luminosity function published by Hemmati et al. (2017; orange dotted line) and model predictions of Popping et al. (2016; grey solid line).