Warren Buffett's investments in Japanese trading companies have raised their international profile and attracted other investors. However, his influence can also lead to a selloff when he reduces his stake in a company. To mitigate this risk, Japan's trading companies are taking steps to diversify their shareholder base. Berkshire Hathaway holds significant stakes in the country's largest trading companies and has raised funds in Japan through bond sales. Buffett has expressed interest in Japanese stocks but will limit his ownership unless given specific approval. The trading companies are also focusing on expanding their businesses to attract growth investors and improve earnings potential.