Key points are not available for this paper at this time.
Gary W. Cox, Frances M. Rosenbluth, Michael F. Thies, Electoral Rules, Career Ambitions, and Party Structure: Comparing Factions in Japan's Upper and Lower Houses, American Journal of Political Science, Vol. 44, No. 1 (Jan., 2000), pp. 115-122
Cox et al. (Sat,) studied this question.