 He was influenced by friends of his father such as Hasegawa Nyozekan, a circle of people identified with the liberal current of political thought during the period of Taishō democracy.After graduating from Tokyo Furitsu Number One Middle School (currently known as Tokyo Municipal Hibiya High School), he entered the Tokyo Imperial University and graduated from the Department of Law in 1937.His thesis "The Concept of the Nation-state in Political Science" earned a Distinguished Thesis Award, and Maruyama was appointed assistant in the same department.