When my site is searched for in Google, it shows the website in Japanese (see the second link in the screenshot below), however the entire website is in English.
Does anyone know why this might be?
Did you recently buy that domain?
You can tell Google to re-crawl the page and update their index using Google Search Console. Or, if you don't have/want a GSC property set up, testing your URL on their Mobile Friendly Test tool can also accomplish the same thing.