The legitimacy of new Lower House members is already being challenged. Two groups of lawyers have filed a set of lawsuits nationwide seeking to invalidate the results of Sunday's Lower House election on the grounds that it was held under a system that does not accurately distribute seats to constituencies according to their population, thereby creating a sharp disparity in the value of votes between more and less populous electoral districts.

For decades, legal actions have been filed to challenge the gap in the value of votes in national elections. Since the current system combining single-seat constituencies and proportional representation was introduced in 1996, the Supreme Court has never ruled a Lower House vote as unconstitutional and invalid, instead prodding legislative action by calling the vote value disparity "a state of unconstitutionality."

The Diet, for its part, responded with a minimum reapportionment of seats in 2013 to contain the maximum disparity in the value of votes within 2 to 1, but continues to drag its feet on an overhaul of the electoral system as called for by top court rulings. And while talks for the electoral system overhaul were set aside when Prime Minister Shinzo Abe dissolved the chamber halfway through the four-year term of its members, the vote value gap widened to 2.13 to 1 in Sunday's snap election due to the continuing population flight from rural to urban areas.