IODP Expedition 332 installed a Long-Term Borehole Monitoring System permanent observatory in a new cased borehole reaching approximately 1,000 m below seafloor. This site (C0002) is located in the Kumano Basin, off the Kii Peninsula, directly above the region believed to be responsible for Magnitude-8 class mega-earthquakes that historically occur at intervals of between every 100 and 150 years. This is also the site of the future ultra-deep riser borehole planned for Site C0002. To help monitor seismic activity within the fault zone and the surrounding accretionary prism with much higher sensitivity and precision, the permanent observatory was installed at Site C0002. This monitoring system consists of sensors, such as a broadband seismometer, a volumetric strainmeter, a tiltmeter, a thermometer array, pressure ports and three-component geophones. It is also to be connected with the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET), which is currently being deployed in this area.