The death Toshikatsu Matsuoka, the first serving Japanese cabinet minister to kill himself since the end of the second world war, is a stark reminder of the professional and cultural stresses that exist in the pressure-cooker of Japanese politics. Prime Minister Shinzo Abe has correctly expressed deep regret at the death of his agriculture minister, who was found hanged in his Tokyo apartment after failing to turn up in parliament to answer questions over a political funding scandal. Matsuoka's drawn-out fall from political grace does not reflect well upon Mr Abe, who repeatedly backed him despite concerns among the opposition and his own party. Matsuoka's eight months as a minister were mired in 'money politics' scandals, as had much of his political career. Despite repeated denials of any wrongdoing, in recent times he faced two key questions - one over claims for 28 million yen in utility fees at his parliamentary office where there were no such charges and another involving campaign donations from companies under investigation of bid rigging. Matsuoka had always been a controversial choice. A pronounced agricultural protectionist, Matsuoka hailed from a political faction that resisted the popular reforms of Mr Abe's predecessor, Junichiro Koizumi. Backed by Mr Abe, he nonetheless used his clout with change-resistant bureaucrats in the powerful Ministry of Agriculture to push free-trade talks. Many across the region are closely watching the situation now facing Mr Abe, fearing that any replacement may be far harder to deal with. His poll numbers are again sliding and his Liberal Democratic Party could lose its Upper House majority during elections next month - an outcome that would put his leadership under considerable pressure. In terms of foreign policy, many question marks remain about Mr Abe's rule. But he has shown promise by rebuilding ties with China and South Korea, as well as driving a tough response to the North Korean nuclear test. There is no guarantee any replacement would be as flexible.