Final answer:
The term describing the cooperative strategy in Japan where business families collaborate for market dominance is Keiretsu. Mitsubishi and Mitsui are examples of the earlier zaibatsu, large family-run conglomerates that were reorganized into keiretsu after World War II.
Step-by-step explanation:
The term that represents a special category of cooperative strategy in Japan, described as "a fighting clan in which business families join together to vie for market share," is Keiretsu. These were influential conglomerates that emerged as a new organizational form, succeeding the earlier zaibatsu after World War II. Keiretsu groups often consist of a bank at the center that provides financing to the manufacturing, supply, and distribution companies within the grouping. Mitsubishi and Mitsui Group were both examples of zaibatsu, which were pre-war Japanese family-controlled vertical monopolies that wielded considerable influence over Japanese industry and politics up until the end of the Meiji period.