After graduating from the law course of Tokyo Imperial University, lie entered the Ministry of Agriculture and Commerce, where he was assigned to make a survey of factory legislation.
In 1922 he went to England for study, and after his return was promoted to the rank of professor, lecturing on social policy. In 1932 he went to Germany for study.
In 1920, when Tokyo University set up a separate department of economics, he became an assistant professor in the department.
In 1939 Hiraga Yuzuru, the president of Tokyo University, ordered both Kawai and another professor named Hiji- kata Shigeyoshi to resign their positions because of their role as leaders of rival factions within the economics department. When Kawai’s case was brought before the Supreme Court in 1943, he was found guilty and condemned to pay a fine.
He was thereafter deprived of any means of expressing his opinions and died of illness before the conclusion of the Pacific War.
He was a liberal who advocated social democracy but opposed both Marxism and nationalism. In 1936 he spoke out openly against the so-called February 26 Incident, when a group of young army officers attempted to carry out a coup d’état, condemning it as an act of fascist violence. In 1938 he likewise spoke out against the proposal by General Araki Sadao, the minister of education, that the president of Tokyo University and other imperial universities should be selected by the government. In the same year his books came under criticism in the Upper House of the Diet, and eventually four works, including Fashizumu hihan (“Critique of Fascism”), were banned, and he himself was indicted.