One day, when Alice was 15, she discovered Japanese Rock music - and discovered a post from a girl called Mimei about an obscure J Rock band. They started talking online - and over the years the relationship developed as the world's online platforms developed - through blogging, online messenger services, social media and video calls. Alice tells Mimei everything and says she's been one of the biggest influences on her life. As they grew up, Mimei moved to Japan, became a professional youtuber with hundreds of thousands of followers, and got married - Alice became an accountant, moved to London, and took up ice hockey. But they've never met...until now. Mimei is flying to London and together they're going travelling round Europe. Four countries, ten days, and two friends who know everything about each other, but have never met before. This is the story of what happens when best friends meet for the first time. Produced by Polly Weston in Bristol.