The banking sector, down 12.3 per cent since the quake, was the second weakest performer on Wednesday, losing 0.6 percent. Mizuho Financial Group, also facing an inspection by financial authorities after it suffered computer system troubles, fell 2.1 percent to 137 yen.
Japanese shares have shed about 7 per cent since the March 11 earthquake and tsunami, and a subsequent nuclear safety crisis, triggered the biggest two-day rout in the market since 1987. In contrast, the MSCI index of Asian shares outside Japan has gained 4.7 per cent.
Domestic fund managers warned the Nikkei faced more downside risk around May.
"This is when firms will publish their earnings forecasts which will seriously sour the market's mood," said Hiroaki Osakabe, a fund manager at Chibagin Asset Management.
"Analysts may put out reports beforehand, but it will be very hard to fully rely on them and price in the quake damage, so the potential declines could be very big."-Reuters