Structural　asymmetry　of　materials　plays　a　crucial　role　in　developing　multipurpose　devices.　Layered　metallic　transition　metal　dichalcogenides　(MTMDCs)　have　been　proposed　as　promising　materials　in　electronics.　However,　they　are　still　subject　to　native　surface　oxidation,　limiting　their　practical　applications.　Combination　of　surface　protection　and　native　surface　oxidation　of　MTMDCs　will　create　asymmetric　structures　for　devices　but　has　yet　to　be　explored.　Here,　we　report　a　bifunctional　NbS2　-based　vertical　heterostructure　derived　from　epitaxially　grown　NbS2　on　MoS2　followed　by　a　natural　oxidation　(MoS2　-NbS2　-NbOx),　which　simultaneously　exhibits　both　high-efficiency　tunneling　conductive　and　memristive　surfaces.　With　the　tunneling　conductive　surface,　the　heterostructure　functions　as　nearly　ohmic　contact　electrodes　with　a　two-dimensional　(2D)　channel　in　lateral　transistors,　delivering　an　enhanced　mobility　similar　to　140　times　higher　than　that　of　the　exfoliated　NbS2　-contacted　device.　With　the　memristive　surface,　the　heterostructure　can　be　used　to　build　high-performance　lateral　or　vertical　memristors　with　low　working　voltages　and　synaptic　functions.　By　combining　both　types　of　surfaces,　a　memristor　array　for　nonvolatile　memory　is　further　developed.　Moreover,　the　memristors　show　a　good　endurance　for　2000　cycles　of　bending　as　flexible　devices.　The　bifunctional　heterostructure　based　on　NbS2　offers　a　strategy　toward　the　future　applications　of　layered　metallic　materials.