Oshiri Tantei Movie 6: Star and Moon

Picture a detective with a butt-shaped head going undercover as an idol on a criminal-run island. Yeah, that's the actual plot, and it works way better than it has any right to. In this sixth movie outing, Butt Detective gets hired by Koala to track down a missing relative who vanished during an idol contest on Stardust Island. Turns out the island is home to the Phantom Thief Academy, an international criminal organization with a scheme called the Dark Age Plan, which sounds ominous for a kids' movie but fits the tone perfectly. Butt Detective disguises himself as a contestant to infiltrate the place, and ends up teaming with Phantom Thief U, a rival thief who's after a gem called the Moonlight Stone. There's also some backstory on Brown, his loyal assistant, which adds a surprising emotional layer. The whole thing is a mystery-comedy wrapped in anthropomorphic character designs from Toei Animation, based on a popular picture book series. If you enjoyed the playful detective energy of Sherlock Hound or the heist dynamics of Lupin III but want something you can watch with younger kids without worrying about content, this hits that sweet spot. Fans of Detective Conan's case-of-the-week format will recognize the structure, just pitched for a broader audience. It's funny, genuinely clever in its mystery setup, and way more charming than the premise suggests.