Article 7That is the procedure when the naikaku (Cabinet) refers the request to dissolve the Lower House (shuugiin; House of Representatives) of the Parliament (kokkai; National Diet of Japan) to the monarch. In simpler terms, a 'snap election' is called. All seats there must stand for re-election. This also makes the Cabinet functionally a 'lame-duck' unless victory in the election is assured. There is *no* such assurance for this election.
The Emperor, with the advice and approval of the Cabinet, shall perform the following acts in matters of state on behalf of the people:
3. Dissolution of the House of Representatives.
It is not official, yet, but given reports like this (English-language source), that is where we are.
August 30th, 2009. Do mark the date on calendar.