From downtown Chicago, a former Nomura Holdings Inc. salesman is taking activist investing to Japan¡¯s smaller listed firms, betting that Prime Minister Shinzo Abe¡¯s corporate governance overhaul is trickling down to less-covered parts of the market.

Masakazu Hosomizu, who works for the ?890 billion ($8.1 billion) RMB Capital Management, urges small and microcap stocks with big cash holdings to improve how they use capital and run their businesses. If they ignore him, he goes hostile. He¡¯s fought several public campaigns over the past two years, with mixed success.

There¡¯s nothing strange about Hosomizu¡¯s brand of activism, but it¡¯s rare for a big U.S. money manager to focus on Japanese stocks that are so small they¡¯re barely noticed by analysts. While that¡¯s partly due to Hosomizu¡¯s unusual past, it¡¯s also another sign of how Abe¡¯s rewritten rules for companies and investors have encouraged shareholders to work more closely with executives.