For Nippon Ishin no Kai and the Democratic Party for the People (DPP), two major opposition parties that have a history of siding with the ruling coalition and each other in parliament, the key challenge in the Upper House election is to convince voters that they are, despite appearances, different from the Liberal Democratic Party.

Ten years after its launch as Japan’s first Osaka-based national political party, Nippon Ishin heads into the July 10 poll with the aim of overtaking the Constitutional Democratic Party as the largest opposition force.

Nippon Ishin currently holds 15 seats in the chamber, six of which are up for re-election. It’s the second-largest opposition party after the CDP, which holds 45 seats. Nippon Ishin is fielding 20 multimember district candidates and 26 proportional representation candidates.

But questions remain about whether Nippon Ishin can broadly expand beyond its traditional Osaka base. Party co-founder and Osaka Mayor Ichiro Matsui's past close relationships with former prime ministers Shinzo Abe and Yoshihide Suga, as well as similar views between Nippon Ishin and the ruling Liberal Democratic Party on defense and constitutional revision, have created another challenge.

As such, Nippon Ishin must sell itself to voters who may wonder why they should cast their ballots for a smaller, less powerful opposition party from Osaka with such a close relationship and similarities with the LDP, rather than going with the ruling party itself.

On Wednesday, Matsui kicked off the campaign in Osaka, calling on voters to cast their ballots for change.

“Politicians all over the country are still stuck with Showa Era status quo thinking," he said, referring to the period between 1926 and 1989. "If Nippon Ishin becomes the top opposition party, it would put pressure on the LDP to up its game.”

On defense, Matsui called for a strong, proactive policy.

“We must have a defense force that can keep the peace to ensure we’re not invaded by other countries,” he said.

Kensuke Takayasu, a political scientist at Seikei University’s faculty of law, predicts that, while Nippon Ishin might pick up a few district seats in urban areas where there are more seats and where its economic policies often hold more appeal, most gains would probably come through the proportional representation system, where voters choose a political party rather than an individual.

“To what extent Nippon Ishin increases its seats depends on how voters see the party, whether they see it as the main challenger to the LDP, and how much voters are frustrated with the (government of Prime Minister Fumio Kishida)," he said. "Nippon Ishin has a record of strong performance at the local government level. But local government does not take care of macroeconomic policy.”

Nippon Ishin’s strategy, he adds, is to paint the CDP as irrelevant and the LDP as not functioning in order to draw disaffected voters from both parties. But that could have its limitations.

“Nippon Ishin also has a very hawkish defense policy and approach to constitutional reform — swing voters could be put off, particularly those from the CDP. And I’m not sure to what extent Nippon Ishin can win over votes from Kishida’s LDP."

He added that hawkish voters are likely to continue to remain with the LDP, while those that are more moderate are probably happy with Kishida and see no reason to vote for another party.

Kishida had long been seen as more of a dovish leader, but he has nonetheless adopted a stronger defense policy supported by hawks within his party.

If Matsui, who will retire from politics next April, is bullish about the prospects for his party in what could be his last national election, DPP leader Yuichiro Tamaki is trying to retain support with what he says is a simple platform.

“Japan is the only country where the real wage index has been declining for 25 years. Just when you think wages have gone up a little, prices go up even more. This is why take-home pay is not increasing and consumption isn’t growing,” Tamaki said Wednesday. "For this Upper House election, I will fight with these two simple promises: raise salaries and protect the country."

The DPP goes into the election merely hoping to maintain its small presence. The party has 12 seats in total, seven of which are up for re-election. The party is running 13 district seat candidates and nine proportional representation candidates.

The DPP has its own concerns about distinguishing itself from other parties, but some support for the ruling coalition as well as a delicate electoral balancing act with other opposition groups complicates those efforts.

Despite attempts by Rengo, Japan's main trade union federation, to get the DPP and CDP to back the same district candidates so as not to split the opposition vote in district races, cooperation has been limited because of the refusal of Rengo and the DPP to back unified candidates that are also supported by the Japanese Communist Party (JCP).

Rengo’s members are key supporters of both the CDP and the DPP. But the latter party's Rengo supporters, as well as the federation's senior leadership, have fundamental policy differences with the JCP and are especially hostile to the idea of any cooperation with it. The DPP’s main union-backed supporters work at private corporations and oppose the JCP's economic policies. They also don’t support the JCP’s opposition to the emperor and are more willing to revise the Constitution.

The DPP has also angered the CDP and Nippon Ishin. They broke opposition ranks and voted for the ruling coalition-backed budget for the fiscal year that began in April, as well as a subsequent supplementary budget, which included measures for dealing with the surge in gasoline prices. The CDP, Nippon Ishin and the JCP opposed the budgets on the basis that they were insufficient to handle inflation.

As sometimes bitter rivals of the CDP and JCP, the DPP and Nippon Ishin had been close for several years — Nippon Ishin wanted the DPP's union votes, and the DPP needed Ishin's power base in Kansai. But the honeymoon is over as Ishin moves away from the LDP while the DPP draws closer to it.

However, the DPP now has to distinguish itself not only from the ruling coalition, whose budgets it supported, but also from its previous association with Nippon Ishin. The two parties cooperated on some legislation following the Lower House election in October, but the DPP’s support of the fiscal 2022 budget led the parties to terminate parliamentary cooperation in March. Nonetheless, the DPP has decided to endorse Nippon Ishin candidate Yuko Kusui in the Kyoto district race to run against CDP veteran Tetsuro Fukuyama.

Between voting with the LDP on the budgets and working with Nippon Ishin, the DPP is facing a very tough election, Takayasu said.

“I don’t think they’ll win more than a few district seats. It’s difficult for (DPP-backed) trade unions to pile up the votes needed to get their preferred candidates elected, and for voters to understand what the DPP stands for.”