The energy price collapse is doing in Japan what the Great Depression and two world wars couldn't: put an end to a century of dominance by its three most prestigious companies.

The trading house descendants of Mitsubishi, Mitsui and Sumitomo, which have dominated the nation's economy for more than 100 years, have seen their profits topped by lesser-known rival Itochu Corp. And analysts predict the firm will be the leading earner until at least fiscal 2018.

Since the end of World War II, Mitsubishi Corp., Mitsui & Co. and Sumitomo Corp. have lived on as the nation's "Big Three" trading companies. They invested in commodities, from shale oil and gas to coal and copper, which led to enormous writedowns when prices began to plummet over the past few years. With the value of their assets in free fall, Mitsubishi and Mitsui were forced last fiscal year to post their first net losses ever.