The hard-hitting journalists at Japan Today wrote up this expository introduction [link now broken] to the world of Japanese talent. Some choice quotes:
Companies like Oscar, Johnny’s Jimusho, Sun Music and Yellow Cab have tremendous power when it comes to their talents, so much so that very few newspapers, magazines or TV stations dare carry negative stories.
“The production companies basically dictate to the networks who to use,” says [anachronistic “crazy foreign guy” Dave] Spector. “The TV stations allow this because they also are given use of top talents in exchange for the B or C list.”