The amendment to the Public Offices Election Law that was hastily enacted this week toward the end of the 150-day regular Diet session, rejiggering the Upper House electoral system in time for the next election in summer 2019, highlights all the more the need for a more fundamental overhaul. The ruling Liberal Democratic Party was seeking to fix a problem facing its own members caused by the readjustment of electoral districts in the previous round of reform to narrow the gap in the vote value between constituencies. However, this amendment has made the proportional representation system for Upper House elections even more complicated and hard to understand for voters.

The number of Upper House seats was raised from 242 to 248 — the first increase since 1970, when two seats were added to the chamber to prepare for the return of Okinawa to Japanese rule in 1972. In this round, two seats were given to Saitama Prefecture — which has the largest number of eligible voters per each Upper House seat allocated — while four were added to the proportional representation segment. Half of the Upper House seats — those representing electoral districts alongside those selected through proportional representation — come up for grabs every three years.

Opponents say that an increase in Diet seats is unacceptable when the nation's population is on the decline and as the government is asking voters for a higher public burden in such forms as a higher consumption tax. Others say there are limits to fixing the disparity in the value of votes between populous and less populous electoral districts while avoiding an increase in the total number of seats. The seats added to the Saitama constituency are estimated to cut the maximum disparity in the value of votes from 3.08 to 1 in the 2016 election to less than 3 to 1 in the next campaign.