Warren Buffett shocked Tokyo markets last August with a $US6 billion ($8.2 billion) bet on the country’s five largest trading houses.

One year on, his investments are paying off. Amid the surge in commodity prices, the collective value of Berkshire Hathaway’s stakes in the five “sogo shosha” has risen by about $US2 billion. That gain of more than 30 per cent has outpaced the benchmark Topix index’s 21 per cent rise, and doesn’t account for dividend income.

Though his stakes in the resource-heavy firms have been a success, the man sometimes known in Japanese media as the “god of investing” hasn’t sparked a groundswell of international followers. Instead, many investors remain sidelined by uncertainty over the pandemic and political leadership.

“He bought at a good time,” said Hideaki Kuribara, an analyst for Tokai Tokyo Securities Co. “I expect him to hold for a long time, and over a long span these investments can be a success. It’s just what you would expect of him.”

The five firms - Itochu, Marubeni, Mitsubishi, Mitsui & Co. and Sumitomo - seem on paper an unusual fit for Buffett’s “buy-what-you-know” philosophy. But with those investments coming just days after Shinzo Abe announced he would step down as prime minister - triggering the first leadership change in more than seven years - many hoped the Buffett brand would spark renewed foreign interest in Japanese markets.

At the time, Japan was weathering the pandemic better than most economies and Yoshihide Suga was soon to take over as prime minister with near-record popularity.

Initially, equities rallied after Buffett’s money arrived, with the Nikkei in February hitting 30,000 for the first time in 31 years. Since that peak, though, the Japan benchmark has gone into a steady decline.

For one thing, COVID-19 cases jumped as the nation’s vaccination campaign lagged those of the US and Europe. Meanwhile, Suga’s ratings have tumbled to record lows as he heads into a general election, with the Olympics in Tokyo doing little to burnish his image.