As Japan's sovereign bond yields languish near zero, the regular payouts to shareholders of the megabanks are starting to appeal to a wider group of investors.

The average dividend yield of the Topix Banks Index, the payout relative to the share price, was at 2.22 percent Thursday. That's a 1.88 percentage point premium over the 10-year Japanese government bond yield, which touched a record low of 0.195 percent last month.

The average indicated dividend yield for the three biggest banks is 2.8 percent.