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We present demography of the dynamics and gas-mass fraction of 33 extremelymetal-poor galaxies (EMPGs) with metallicities of $0.015-0.195~Z_\odot$ and lowstellar masses of $10^4-10^8~M_\odot$ in the local universe. We conduct deepoptical integral-field spectroscopy (IFS) for the low-mass EMPGs with themedium high resolution ($R=7500$) grism of the 8m-Subaru FOCAS IFU instrumentby the EMPRESS 3D survey, and investigate H$\alpha$ emission of the EMPGs.Exploiting the resolution high enough for the low-mass galaxies, we derive gasdynamics with the H$\alpha$ lines by the fitting of 3-dimensional disk models.We obtain an average maximum rotation velocity ($v_\mathrm{rot}$) of$15\pm3~\mathrm{km~s^{-1}}$ and an average intrinsic velocity dispersion($\sigma_0$) of $27\pm10~\mathrm{km~s^{-1}}$ for 15 spatially resolved EMPGsout of the 33 EMPGs, and find that all of the 15 EMPGs have$v_\mathrm{rot}/\sigma_0<1$ suggesting dispersion dominated systems. There is aclear decreasing trend of $v_\mathrm{rot}/\sigma_0$ with the decreasing stellarmass and metallicity. We derive the gas mass fraction ($f_\mathrm{gas}$) forall of the 33 EMPGs, and find no clear dependence on stellar mass andmetallicity. These $v_\mathrm{rot}/\sigma_0$ and $f_\mathrm{gas}$ trends shouldbe compared with young high-$z$ galaxies observed by the forthcoming JWST IFSprograms to understand the physical origins of the EMPGs in the local universe.

EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely-Metal Poor Galaxies