Celebrating the series' 10th anniversary, Keroro the Movie 4 opens as a mysterious giant being appears on earth. Nobody knows what it is, but it looks like trouble. The Keroro Platoon, a band of alien invaders, has been on the blue planet for many years and has a good relationship with some humans. The soldiers must use advanced military technology from their planet to investigate the mysterious monster. They begin their search, picking up clues along the way. These clues take them out of Japan and on a trip around the world, to Australia, the United States and Africa, finally stopping in Mont-Saint-Michel in France. There, Keroro and his men meet an enigmatic girl named Shion, who holds the mysterious Dragon book. The more things the Keroro Platoon unveils about Shion, the more dangerous their lives become. This series has become very popular over the past decade, but compared to another fantasy anime, Doraemon, which was very popular in the 80s and 90s, it is lacking in character development, creativity and structure. However, it offers plenty of laughs for Keroro fans. The DVD comprises some interesting special features, including a short movie, Kero-Zero, that explains Keron life before the platoon invaded earth, and a preview for Keroro the Movie 5.