If you loved Diebuster: The Movie, try Mobile Suit Gundam GQuuuuuuX -Beginning-
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by Kazuya Tsurumaki, and they sit in Action / Animation / Drama / Science Fiction territory. If that's the register that drew you to Diebuster: The Movie, the second film will land in a comparable space — through a different lens.
What Mobile Suit Gundam GQuuuuuuX -Beginning- is
You live in a peaceful space colony, but when you meet a war refugee, your life is drawn into a high-stakes mobile suit dueling sport. The filmmakers balance action and drama in this sci-fi world.

