The 15th Japan Expo was held in July in Paris so you missed it. I don't think they have announced where and when the 16th japanese Expo will be held but it is Europe’s largest Japanese pop culture event.
Launched in 2000 by a group of passionate young French fans of Japanese culture, Japan Expo is an event that showcases the diversity of Japanese pop culture. It celebrates a wide variety of genres within Japanese culture, from pop culture such as film, fashion, music, game, anime and manga, to traditional culture, literature, Japanese cuisine, kimono and cultural performing arts. Held at the venue are film screenings, fashion shows, live concerts, as well as exhibits and promotional events such as new product unveilings and lectures by cultural figures. The Japanese Expo in 2013 had an attendance of 230,000 people.