The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) program is a coordinated, multiexpedition drilling project designed to investigate fault mechanics and seismogenesis along subduction megathrusts through direct sampling, in situ measurements, and long-term monitoring in conjunction with allied laboratory and numerical modeling studies. The fundamental scientific objectives of the NanTroSEIZE drilling project include characterizing the nature of fault slip and strain accumulation, fault and wall rock composition, fault architecture, and state variables throughout the active plate boundary system to a depth of approximately 7000 meters below seafloor (mbsf). Integrated Ocean Drilling Program (IODP) Expedition 326 is slated to begin drilling the main ultradeep borehole with "top hole" operations to pilot the hole, set casing to approximately 800 mbsf, and install the wellhead to be used in later deep riser drilling at Site C0002.