The Diet's fragmented opposition forces took a step toward consolidation as Nippon Ishin no Kai (Japan Restoration Party) and Yui no To announced they will operate as a unified party in the Lower House this autumn.

The agreement, made Wednesday, merges Nippon Ishin's 32 and Yui no To's nine members in the Lower House and follows an earlier agreement the two parties forged to cooperate in the Upper House. The Nippon Ishin/Yui no To bloc of 41 members will thus become the second-largest opposition force in the powerful lower chamber after the Democratic Party of Japan, which has 55 members.

A formal merger is expected by the end of summer. While the two parties agree on most of the issues regarding increased autonomy for local governments, there are a few areas, such as collective self-defense, where they differ. Nippon Ishin's position was closer to that of the LDP-New Komeito coalition than Yui no To's.

Disagreement over cooperation with Yui no To led Nippon Ishin to break up last month. Nippon Ishin co-leader Toru Hashimoto, with his mostly Osaka loyalists, had long pushed for a Yui no To merger but was opposed by former co-leader Shintaro Ishihara, who disliked the resistance that Yui no To and Hashimoto showed to formally rewriting, as opposed to reinterpreting, the Constitution.

On Wednesday, 19 members of the Nippon Ishin splinter group loyal to 81-year-old Ishihara registered with the Lower House as the Next Generation Party, whose official head is 74-year-old Ishihara ally Takeo Hiranuma.