[2] In 2006, Shii became the first JCP chairman to visit South Korea, where he traveled to an international conference of Asian political parties.

He visited the site of Seodaemun Prison and paid tribute to the memory of Korean anti-colonial activists who were imprisoned during the period of Japanese colonialism.

In 2016, Shii proposed a "national coalition government", promoting the joint fielding of candidates with other opposition parties.

That year, he amended the JCP constitution to accept the Japan Self-Defense Forces and the Imperial House for the time being.

[5] On 21 January, party newspaper Shimbun Akahata published commentary piece titled "Clear deviation from the constitution and platform", rebutting his words and actions; Shii called the commentary "correct" at a press conference on 23 January, saying calls to introduce a public election system was a violation of the party constitution.

[11] A position paper issued by the party said that China's "great-power chauvinism and hegemonism" were "an adverse current to world peace and progress.

[15] Despite being on starkly opposite ends of the ideological spectrum, Shii took part in a dialogue with former prime minister Junichiro Koizumi in 2020, where they discussed their mutual love for classical music.