Diebuster is the OAV sequel based on Hideaki Anno's original Gunbuster series. Considering the impact of the original it's hard to image how incredibly overlooked this 6-part OAV follow-up series is. Tsurumaki is the one bringing the 15-year old original back to modern standards, completely in the spirit of Gainax, and doing a pretty great job at that.
Gunbuster is the series that kick-started Anno's career. An important event in the history of anime, as he would later go on to direct Evangelion. At the same time, it marks the rise of legendary anime studio Gainax. The original is a series that still stands its ground today, but is somewhat unknown among younger anime fans.
Tsurumaki's sequel is not so much a continuation of the original story, but an update of the source material to match the need of today's anime viewer. It shares some common elements with the original, often smaller details (like flight suit design) but also the general story outline. The main plot though stands firmly on its own and has minimal links with the original series. Not a bad choice, as both series do target a somewhat different audience.
Diebuster is about a young girl (Nono) running away from home to make it big in the military. No time for mech school this time, as mech pilots are chosen by the natural presence of supernatural abilities (or a special state of mind as described in the series). Nono is obviously lacking but still manages to infiltrate the group of prodigious kids. From there on, things grow more grotesque with each passing episode, resulting in an insane space showdown pretty much blowing up the whole universe as we know it. Standard anime stuff in other words.
Visually Diebuster received a serious boost. The style lies closer to series like FLCL and Abenobashi than it resembles the original. Bold, flashy colors and fatter outlines, animated with strong, extreme movements. It's an acquired taste, and those hoping for some of the magic of yonder will probably be disappointed, but I liked it a great deal. The level of animation does decline a little as the series goes on, coming to a virtual standstill in the first half of the last episode, only to go completely mental for those last 20-25 minutes. I guess they were saving up on budget for a reason.
The soundtrack is quite forgettable and the voice acting as you'd expect from an anime like this. It's always fun to see the galaxy saved by a character with the voice of a 4-year old Japanese toddler, though I'm sure the joke will be lost on many. It's all pretty standard stuff in the audio department, apart from the magnificent scream of the final galaxy-eating enemy. That one spooked me for a minute and is used with great effect.
Those hoping for a serious sci-fi series will be left in the cold. It is after all a Gainax product, so there's plenty of fanservice material (often so silly they must've been well aware of it) and crazy anime nonsense flying around. It's not so much sci-fi as it is comedy/mecha with some strange blurps of science thrown in (which reminds me, I did miss the science interludes of the original).
Diebuster is a series aimed at fans of the original who still have a place in their heart for modern anime. Those people are admittedly a little rare, so in the end it's not all that strange that the series never became that popular. I must be one of the few though, as I appreciated all the grotesque but fun-filled idiocies for what they were. Pure and simple anime fun with a good wink. Hard to recommend, this one, but if you think you fit the description, well worth the try.