A large-scale CCS demonstration project is being undertaken by the Japanese government in the Tomakomai area, Hokkaido Prefecture, Japan. The objective is to demonstrate the viability of a full CCS system, from CO2 capture to injection and storage. One hundred thousand tonnes/year or more of CO2 is being injected and stored in offshore saline aquifers in the Tomakomai port area. The implementation of this project has been commissioned to Japan CCS Co., Ltd. (JCCS) by the New Energy and Industrial Technology Development Organization (NEDO) with the subsidies for the operating expenses by the Ministry of Economy, Trade and Industry (METI). The CO2 source is a pressure swing adsorption offgas from a hydrogen production unit (HPU) of an oil refinery located in the coastal area of Tomakomai Port. The HPU provides CO2 rich offgas to the Tomakomai demonstration project CO2 capture facility via a 1.4 km pipeline. In the capture facility, gaseous CO2 of 99% or higher purity is recovered from the offgas by a commercially proven amine scrubbing process with a design capacity of 200,000 tonnes per year. At the injection facility, the gaseous CO2 is compressed and injected into two different offshore reservoirs (Moebetsu Formation/sandstone layers and Takinoue Formation/volcanic rocks layers) by two dedicated deviated injection wells. The storage points are located at 3 to 4 km offshore. The project is scheduled to run between the period of JFY 2012 - 2020 (JFY is from April of calendar year to following March). The injection of CO2 began in April 2016. The injection of CO2 will be conducted for three years and monitoring for five years. The injection target is 300,000 tonnes in total over three years. The main features of this project are: 1) Extensive monitoring system in seismically active country, 2) Deviated CO2 injection wells drilled from onshore to offshore, 3) Marine environmental survey by domestic law reflecting London Protocol, 4) Low energy CO2 capture process, 5) Injection of CO2 near urban area.