Prof. K. Tsuchiya is a pioneer in the field of Biomedical Engineering Research in Japan. He started a collaborative research with Prof. S. Sakakibara of Tokyo Women's Medical College (Heart Institute of Japan) in 1966, focusing on an application of fluidics for circulatory assist devices. After Prof. M. Umezu's participation in the middle of 1970s, research direction on biomedical engineering at Waseda University was shifted to be more clinical oriented. They developed a pulsatile cardiopulmonary bypass system for clinical use. Several advantages of pulsatile perfusion were demonstrated through clinical trials. After Dr. Y. Shiraishi joined as a Waseda team member in the middle of 1990s, they had a rapid progress on the analysis of natural cardiovascular system, while developing a mock circuit, called "Waseda mechanical circulatory system". This simulator consisted of anatomi-cally and hydrodynamically identical components, such as U-shaped aorta, spherical-shaped left atrium, and conical-shaped left ventricle, etc. It has been confirmed that our sophisticated mock system has a high potentiality in terms of an analysis of cardiovascular system as well as an evaluation of artificial organs and/or surgical treatments.