InuYasha the Movie 2: The Castle Beyond the Looking Glass
ANN; IMDb; Rotten Tomatoes; Wikia; Wikipedia
Based on the TV series InuYasha. It starts with our heroes killing Naraku, which of course they've been trying to do throughout the series (and I'm not exactly sure when this is set in relation to the series). So, Kagura gets something she's always wanted: freedom from Naraku. So does Kanna, and Kohaku. And Miroku's wind tunnel disappears. Meanwhile, Kanna and Kagura are talking, via a mirror, with someone called Kaguya, who claims to be a celestial being. She wants them to collect various items that will release her. Kagura agrees to do this because Kaguya has promised her complete freedom from Naraku (which suggests he may not be quite as dead as he seems to be).
Back in her own time, Kagome is in school, learning the legend of a Moon Princess named Kaguya, coincidentally. And Miroku, visiting old friends, learns that his grandfather had imprisoned this demon, Kaguya, in a mirror years ago. And later, Kagome and InuYasha meet a young man who is an acenstor of Kagome's friend Hojo. He's guarding an ancient relic that Kaguya needs to help her cast the world into eternal night.
And at some point, Kaguya kidnaps Kagome, transporting her to a castle within the mirror, and the others have to try to rescue her. And Kaguya begins to transform InuYasha into a full demon, but Kagome stops that, with a kiss. Then Kagura and Kanna attack Kaguya, and Naraku returns, and so does Miroku's wind tunnel. Naraku then tries to absorb Kaguya, and fails. Well, everyone does some fighting, I guess. I don't remember it that well at the moment, but in the end, things pretty much go back to normal. As they always do.... And that's all I can think to say right now, but I may update this if I watch the movie again sometime.