A lawyer representing shareholders suing Fukushima nuclear plant operator TEPCO for $68 billion said Monday the company's executives should be prepared for misery and poverty to make amends.

Hiroyuki Kawai, who is leading 42 shareholders in their bid for compensation from Tokyo Electric Power Company for negligence over the tsunami-sparked disaster at the plant, said senior managers must be made to pay.

"Warnings have to be issued that, if you make wrong decisions or do wrong, you must compensate with your own money," Kawai told a press conference.

"You may have to sell your house. You may have to spend your retirement years in misery. In Japan, nothing can be resolved and no progress can be made without assigning personal responsibility."

The lawsuit, which is demanding a record 5.5 trillion yen, claims that 27 current and former executives of TEPCO ignored warnings by researchers about the possible damage to the Fukushima Daiichi plant that a huge earthquake and tsunami could cause.

The Fukushima crisis might have been prevented, had TEPCO taken the research seriously and carried out simple preventative measures, such as placing an emergency power source on higher ground, Kawai said.

Reactors at the plant were sent into meltdown when huge waves swamped their cooling systems following the March quake.

Radiation leaked over a large area, forcing tens of thousands of people from their homes and rendering vast areas unfarmable.

No one from TEPCO has been arrested and there is no active criminal investigation into the case, despite a number of inquiries that found serious shortcomings in the company's emergency safety procedures.

TEPCO declined to immediately comment on the ongoing civil case.