For identical bosons interacting via a large s-wave scattering length, Efimov states and their associated universal few-body bound states appear. For fermions, in particular in a mass-imbalanced two-component Fermi system with a large inter-species s-wave scattering length, even richer universal few-body and many-body states are expected to appear from the competition between a repulsion by the Pauli exclusion principle and the attraction induced by the resonant interaction. I first explain universal three-body and four-body physics in the mass-imbalanced Fermi system, and how they evolve as the mass ratio and the s-wave scattering length are varied. Then, I discuss how these few-body knowledge can be applied to quantum many-body problems of the mass-imbalanced Fermi system.