This film is a follow-up to the Haikyuu!! anime. It's actually the first of two movies intended to complete the manga story and conclude the show. In Dumpster Battle, the Karasuno High volleyball team are in the tournament quarter finals and going up against their rival school Nekoma High, which includes amongst it's roster main character Shoyo Hinatao's friendly rival Kenma Kozune, the master strategist.
Even though it's based on the existing manga storyline, I think this movie has the unfortunate circumstance of coming out after the Slam Dunk movie. They're both films that 1) take place over the entirety of one basketball game and 2) focus on a character other than the main one. However, SD had a more serious backstory and a more stellar animation style which results in some unfair comparisons between the two. Dumpster Battle's only sin is that it isn't SD, otherwise it's a fine made film.
The first third might a feel a little basic, but the movie picks up speed resulting in a very engaging piece. The movie kinda feels like a game of chess as the characters must strategize against their opponents, and you're left wondering how Karasuno can win.
The movie makes the interesting choice of making the main character not the stars but their rival. Kenma's story arc becomes more and more interesting as the film goes on. He's the absolute opposite of a what a typical sports rival is (or at least from a western perspective). He's introverted and playing isn't his passion, The crux of the film is what makes Kenma tick and what makes him passionate, and it's an interesting character study.
This is one of those many anime movies where they don't have big budgets, but the animators are all really professional with fluid animation and detailed backgrounds.
Haven't seen the show, but this feels like it delivers the volleyball action, character and sports drama that the fans like. Newcomers like me should be able to follow the main story, but be warned that there are a lot of peripheral characters you won't know nothing about. (I initially got the coaches and fans in the bleachers mixed up with which team they support.)
Recommended. This is a solid movie that should delight fans and provide a distinct yarn for the uninitiated.