アブストラクト：
We investigate Lya, [OIII]5007, Ha, and [CII]158um emission from 1,125 galaxies, composed of 1,098 Lya emitters (LAEs) at z=4.9-7.0 identified by Subaru・HSC narrowband surveys and 29 galaxies at z=5.148-7.508 with deep ALMA [CII]158um data in the literature. We find that (1) a positive correlation between the Ha equivalent width (EW) and the Lya EW, (2) a turn-over trend of the [OIII]/Ha ratio with the Lya EW, (3) a 4.5sigma negative correlation between a [CII] luminosity to star-formation rate ratio (L_[CII]/SFR) and EW^0_Lya. These results are explained by a simple anti-correlation between EW^0_Lya and metallicity, indicative of the detections of the very metal-poor (~0.04 Zo) galaxies with EW^0_Lya~200 A.