Oshiri Tantei Movie 6: Star and Moon

Koala asks Butt Detective to find a relative who vanished after entering an idol competition, leading the investigation to Stardust Island. The contest is only one face of the island, however. It is also home to Phantom Thief Academy, an international criminal organization led by Phantom Thief G, who is quietly advancing a conspiracy known as the Dark Age Plan.

To get close to the truth, Butt Detective enters the competition disguised as an idol. At the same time, he joins forces with Phantom Thief U, who wants to reclaim the stolen Moonlight Stone. Between stage performances and criminal schemes, the case begins exposing secrets that reach unexpectedly into Brown's past.