Rishi Sunak has arrived in Tokyo to announce a new defence partnership with Japan and support £18bn of private business deals, ahead of the G7 summit aimed at addressing the threats of Russia and China. Before the gathering of world leaders in Hiroshima on Friday, Sunak is meeting Japan’s prime minister, Fumio Kishida, to discuss more defence cooperation in the face of China’s increasing belligerence towards Taiwan. They will unveil a pact, the Hiroshima accord, which involves a duty to consult each other on some military decisions and further exercises in the Indo-Pacific by the Carrier Strike Group, a Royal Navy unit. The UK prime minister is understood to view Japan as strategically important and a like-minded country that shares his interest in technology and innovation. The pair will discuss supply of semiconductors – used in cars, smartphones, medical devices and other gadgets – at a time of global concern about reliance on production in Taiwan when it is facing a threat from China. On Thursday, Sunak also visited a naval base and then hosted a UK business summit in Tokyo for Japanese corporations including Toshiba, Sumitomo and Mitsubishi, claiming they are committing £18bn of investment to the UK in windfarms, property and other projects. He will be accompanied by Octopus Energy, a UK utility supplier expanding to Japan, and Mott MacDonald, an engineering company advising on offshore wind projects, as well as at least three UK startups, Oxentia, Transreport and Winnow. However, he was pressed on Thursday about the attractiveness of the UK as a business destination after a leading carmaker said Brexit was proving an obstacle. Speaking to broadcasters, he said: “It’s something that car manufacturers across Europe, not just in the UK have raised as a concern. And as a result of that we are engaged in a dialogue with the EU about how we might address those concerns when it comes to auto manufacturing more generally. I’m going to be meeting the chief executive of Nissan later today … they’ve invested a billion pounds in the north-east for electric vehicle manufacturing. “Other Japanese business leaders are meeting today to announce a total investment of £18bn into the UK and part of that investment is coming because we’ve joined the trans-Pacific trade partnership that opens up opportunities for British car manufacturers and creates more jobs at home.” Defending himself against criticism that his optimism about the economy was not being felt by millions at home, he said: “I know things are tough right now but there are signs things are improving. A vote of confidence from Japanese companies creating jobs at home. That’s a good thing for the UK.” On his trip to the G7 Sunak is being accompanied by his wife, Akshata Murty, on their first official visit since he entered No 10. Sunak is likely to have one-on-one meetings with the French president, Emmanuel Macon, and the Indian prime minister, Narendra Modi. However, No 10 is not expecting Sunak to meet bilaterally with the American president, Joe Biden, whose trip to Asia for the summit is being curtailed over uncertainty surrounding the US debt ceiling. Washington has taken a harder line against Beijing than some European countries, with Macron saying last month Europe should not get “caught up in crises that are not ours”. Sunak’s other priority will be pressing other world leaders to double down on support for Ukraine.