The collapse of the political marriage of convenience between Nippon Ishin no Kai (Japan Restoration Party) co-leaders Toru Hashimoto and Shintaro Ishihara was long in coming, surprised no one, and suggests that, when it comes to Japanese political mergers at least, Rudyard Kipling was correct when he warned East and West could never meet.

It also forces the children of the marriage — the 53 Lower House and nine Upper House Nippon Ishin members — to find new homes, likely in places favored by one of the parents, like Yui no To in the case of Hashimoto, or Your Party, in the case of Ishihara. They will also have the option of forming yet another opposition party, or even joining the ruling Liberal Democratic Party or the Democratic Party of Japan.

For his part, Hashimoto told reporters in Osaka on Thursday he has no regrets about the often stormy relationship.

“In the end, my management of Nippon Ishin (as co-leader) was insufficient. I like Ishihara-san. He’s a very interesting person. We had differ-ences but it was a good experience. I learned a lot about Nagata-cho,” Hashimoto said.

The divorce comes a year and a half after Hashimoto announced that Nippon Ishin, formed to turn the Osaka political group Osaka Ishin no Kai (One Osaka) into a national movement for seeking more local autonomy from Tokyo, would tie up with former Tokyo Gov. Ishihara and his mostly Tokyo or eastern-based allies.

Hashimoto’s supporters in the city and prefectural assemblies were young, idealistic, and firmly committed to merging the city of Osaka with Osaka Prefecture. They did not hide their disappointment with his marriage partner. While Nippon Ishin’s platform for the December 2012 Lower House election promised to make the Osaka merger a reality, Ishihara had hinted in past statements that he was opposed to turning Osaka into the equivalent of Japan’s second capital.

Nippon Ishin won 54 seats, but that was still less than the 100 to 150 seats some pundits predicted earlier in the year. This was mostly due to voter concern over the clear differences separating its Hashimoto and Ishihara factions. For example, in addition to worries in the party over how serious Ishihara was about the Osaka merger, there were sharp differences over nuclear power as well.

Hashimoto wanted to get out of nuclear and into renewable energy, but was opposed by Ishihara and his pro-nuclear allies. The resulting manifest thus promised only to “fade out” of nuclear power, a vague phrase that could be interpreted however the reader wished.

The two were also at odds over the Trans-Pacific Partnership negotiations. From the beginning, Hashimoto endorsed joining the TPP talks. Ishihara, however, was skeptical of the trade treaty, as were many other Nippon Ishin members from rural areas.

But it was their fundamentally different views on constitutional revision that ultimately caused the split. For Hashimoto, the issue is important but not the overriding issue. He also sees himself as more practical-minded than Ishihara, and favors reforming the Constitution by properly amending it.

Ishihara and his backers don’t want amendments but an entirely new Constitution. They were particularly irked that Hashimoto’s Osaka Ishin has only a plurality in the city assembly and needs New Komeito, which is cautious, at best, about constitutional revision.

What next? About two dozen Nippon Ishin Diet members are from Kansai. Most back Hashimoto, though how many will go to Yui no To is uncertain. But few are expected to join Ishihara. Generational and geographical gaps mean their differing world views are likely to find a home in not one, but several other parties.