Two-dimensional (2D) hetero-nanosheets are currently the focus of intense study due to the unique properties that emerge from the strong interplay between two low-dimensional nanomaterials with different properties. However, the properties and new phenomena based on the strongly interacting, two 2D hetero-nanosheets in a 3D hierarchical architecture have yet to be explored. Here, we unveil the surface redox charge storage mechanism of surface-exposed WS2 nanosheets assembled in a 3D hierarchical heterostructure using in-situ synchrotron X-ray absorption and Raman spectroscopic methods. The surface dominating redox charge storage of WS2 is manifested in a highly reversible and ultrafast capacitive fashion due to the strong interaction of hetero-nanosheets and the 3D connectivity of the hierarchical structure. In contrast, compositionally identical 2D WS2 structures fail to provide a fast and high capacitance with different modes of lattice vibration. The distinctive surface capacitive behavior of 3D hierarchically structured hetero-nanosheets is associated with rapid proton accommodation into the in-plane W-S lattice (with the softening of the E2g bands), the reversible redox transition of the surface-exposed intralayers residing in the electrochemically active 1T phase of WS2 (with the reversible change in the interatomic distance and peak intensity of W-W bonds), and the change in the oxidation state during the proton insertion/deinsertion process. This proposed mechanism agrees with the dramatic improvement in the capacitive performance of the two hetero-nanosheets strongly coupled in the hierarchical structure.