Monoidal categorification is a categorical-approach to studying (quantum) cluster algebras from the perspective of monoidal categories. In this talk, I will discuss the categorification of quantum groups using quiver Hecke algebras by Khovanov-Lauda and Rouquier, and explain how quiver Hecke algebras provide a monoidal categorification following the work of Kang-Kashiwara-Kim-Oh. I will then explain how the crystal theory can be used in studying the monoidal categorification, and present my recent result on quantum twist automorphisms and crystals. This is partially based on joint work with Woo-Seok Jung (arXiv:2507.01306).