A Japanese man in his 20s was referred to our hospital with a two-month history of abdominal fullness and leg edema. Abdominal computed tomography revealing massive ascites and ostial blockage of the main hepatic veins, and angiographic evaluation demonstrating obstruction of the main hepatic veins yielded a diagnosis of Budd-Chiari syndrome (BCS). Diuretic agents were prescribed for the ascites but failed to provide relief. The patient was referred to our department for further evaluation and treatment. Angiography showed ostial obstruction of the main hepatic veins, with most of the portal hepatic flow draining from an inferior right hepatic vein (IRHV) into the inferior vena cava (IVC) thorough an intrahepatic portal venous and venovenous shunt. Access between the main hepatic veins and IVC was impossible, but cannulation between the IRHV and IVC was achieved. Because of the venovenous connection between the main hepatic vein and the IRHV, metallic stents were placed into two IRHVs to decrease congestion in the hepatic venous outflow. After stent placement followed by balloon expansion, the gradient pressure between the hepatic vein and IVC improved remarkably. The ascites and lower leg edema improved postoperatively, and long-term stent patency (6 years) was achieved.