He voted for Tsutomu Hata in the next prime minister election, believing the LDP should be blocked from forming a government at all costs.

[18] He played a role in investigating the HIV tainted blood scandal beginning in 1995, when he was contacted by the plaintiffs defense team and became convinced of the government's responsibility in the issue.

He presided over the ministry's apology in February, and in July he took the stand to question Hideo Abe, the former head of the AIDS research team.

He attempted to defend his seat in Saitama's 5th district in an election centered around volunteers,[21] running against both Zenjiro Kaneko of the New Frontier Party and Nobuhiko Fukunaga of the LDP.

He ultimately lost in a close three-way election only decided by five points to Fukunaga, but was re-elected to the House after being placed on the Northern Kanto proportional representation block.

In the Diet, he submitted several bills, including one to allow for separate surnames for married couples, one to create an Administrative Surveillance Board, and a law further criminalizing possession of child pornography.

[25] He then serviced as campaign secretary for Kan when he was challenged again by Yukio Hatoyama inside the party in September, to which he ultimately lost.

[28][29] He also founded the Ryounkai political group in 2002 along with Seiji Maehara and Yoshito Sengoku, which mainly functioned as a conservative pressure organization inside the DP.

In 2005, When Okada stepped down due to his failure in the national elections, he supported his own ally, Seiji Maehara, to succeed him.

In September 2008, Edano briefly debated running for party representative to avoid Ozawa being re-elected without a vote due to the failures of others, such as Naoto Kan to announce a challenge.

Edano was re-elected by a 20-point margin in the landslide 2009 Japanese general election, in which he and the Democratic Party were swept into power.

[35] At the end of May in 2010, the Hatoyama Cabinet resigned, and in the election for successor, Edano supported Naoto Kan along with Seiji Maehara and Katsuya Okada.

[38] In early march, due to the resignation of Foreign Minister Seiji Maehara, he served in the office on an interim basis until Takeaki Matsumoto was appointed.

[citation needed] On March 11, 2011, less than two months after taking office as the Chief Cabinet Secretary, the Tōhoku earthquake and tsunami and Fukushima nuclear accident occurred.

Edano took on the role of the government's main spokesman on the response to both events, beginning to report on recovery every single day.

The strain put on himself as a result, and his energetic response style led to him being compared to Jack Bauer from 24 in overseas media.

[43] The United States Nuclear Regulatory Commission released internal documents on the aftermath of the Tokyo Electric Power Company Fukushima disaster.

Among them was a record where Edano requested that a nuclear power expert be permanently placed in the Prime Minister's Office as a form of support for Japan,[44] with the Yomiuri Shimbun saying Edano made one more request, stating that the expert in question not be allowed into the Prime Minister's residence.

"[47][48] In April 2011, the Ministry of Education, Culture, Sports, Science and Technology set a safety standard for children of 3.8 microsieverts per hour, equivalent to 33 millisieverts per year, but left local governments to decide decontamination methods and didn't take proactive measures.

Initially, he stated that he would instead support the cabinet as a private citizen, but was then appointed as the Ministry of Economy, Trade and Industry ten days later by Noda following Yoshio Hachiro's resignation due to alleged inappropriate behavior related to the nuclear meltdown in Fukushima.

There is no way we can restart operations without thoroughly checking safety", and expressed the idea that an eye should be kept on the evaluation and judgment by the Nuclear Regulation Authority, which was set to be created in September that year.

[66][67] Edano ran for party leadership in the September election, but in a battle with Seiji Maehara and the Ryounkai, lost.

[citation needed] On the afternoon of September 28, 2017, at a general meeting of members of both houses of the Democratic Party in preparation for the 2017 Japanese general election - which Abe had called only three weeks after the DP leadership election - leader Seiji Maehara proposed de-facto joining the new party founded by Yuriko Koike, Kibō no Tō.

"[71] On September 29, Koike stated at a regular press conference that she would exclude left-wing and liberal members of the Democratic Party, subject to acceptance of the security legislation and amendment of the constitution.

[5][6][72] In the early hours of September 30, Kyodo News reported that Edano had begun to consider running as an independent, or possibly forming a new party for now party-less liberals of the former DP.

[74][75] That night, Edano, Akira Nagatsuma, Kiyomi Tsujimoto, Shoichi Kondo, and Tetsuro Fukuyama met in a hotel room in Tokyo to discuss the possibility of forming a new party.

[76] Also that morning, Edano visited RENGO Headquarters and met with President Rikio Kozu, explaining the situation and his plans to form a new party.

"[82][83][84] The next day, Nagatsuma submitted a notification of the formation of the new party to the Ministry of Internal Affairs and Communications, which was accepted.

In the general election that month, The CDP-SDP-JCP coalition made a shocking finish above Kibō no Tō, overall placing second with five more seats than the party.

[103] He personally considers himself a "mainstream conservative", still reportedly saying to former Prime Minister Tomiichi Murayama that he will "form another liberal government while you're still well".