The Lower House on Tuesday unanimously adopted a resolution condemning North Korea's nuclear test, calling the action an "outrage" and demanding that the government strengthen its sanctions against Pyongyang.
The Upper House is expected to adopt a similar resolution as early as Wednesday.
"North Korea clearly violated the United Nations resolution, the joint statement issued by the six-party talks and Japan-DPRK Pyongyang Declaration and carried out a second nuclear weapons test," the resolution states.