We explored the parsec-scale nuclear regions of a sample radio-loud narrow-line Seyfert 1 galaxies (NLSy1s) using VLBI Exploration Radio Astronomy (VERA) wideband (at recording rate $16\,\mathrm{Gbps}$) polarimetry at 22 and 43 GHz. Our targets include 1H 0323+342, SBS 0846+513, PMN J0948+0022, 1219+044, PKS 1502+036 TXS 2116-077, which are all known to exhibit $\gamma$-ray emission indicative ...