Medusa is a story of siblings Tatsuo and Yoko, that starts during the peak of the turbulent Vietnam War years. Tatsuo is a straight-laced Tokyo College student, the adopted son of a liberal politician. His sister Yoko is a revolutionary who plans to change Japan through protest; he plans to change Japan by rising in politics. Despite their similar views and love for each other, their different approaches lead to a conflict that drives them apart.