I'm not sure which anime resource you're referring to. The term 'canary in a cage' usually appeared in novels, comics, or movies, and it did not necessarily refer to specific anime works. If you can provide more information, I can try my best to help you find the relevant information.
Sasuke could be a likely candidate. Despite their complex relationship, Sasuke has a deep bond with Naruto. If he were to find out that Naruto was in such a predicament, he would likely rush to his aid, using his Sharingan and powerful ninja skills to take on whoever is guarding the cage.
I'm not entirely sure, but it could potentially be a novel that has a lot of elements that seem trapped or caged in a sense. Maybe the characters are trapped in their social status, like in a Jane Austen - like novel where the female characters are caged by the social norms of marriage and propriety. Or perhaps it's a novel where the story itself seems to be in a cage, not allowed to expand too far beyond a certain set of ideas or events. It could also be a term used by a specific group of readers or critics to describe a novel that gives the impression of confinement.
In most cases, 'The Cage' is not based on real events. It might draw inspiration from various sources but doesn't represent actual happenings. The plot and characters are crafted for entertainment and narrative purposes.
I'm not sure what kind of anime you're referring to. However, Spirit Cage was an original Chinese animation that told the story of a supernatural world. In addition, there were many other types of anime such as Japanese anime and Korean anime. Can you provide more information? This way, I can better answer your question.