In Accel World's jargon Zero Fill is when, due to lack of willpower, the signal transmitted to an avatar is reduced to zeros only. A fitting analogy for a series which, despite some promising foundations, an unconventional protagonist and a general high level of visual polish, ends up being brainless and largely unfulfilling.
It's not surprising given how exposition and the script in general is delivered like a kudgel to the forehead. Regardless of ongoing events, be that an all out war or impending attack , meticulous explanations as to what is going on are sure to follow. Combined with the protagonist's ostensibly chivalrous but archaically chauvinistic desire to protect the gaggle of women folk who flock around him, it's not long before genre titans like Bleach and Naruto begin to exert their influence.
The start is promising: Harayuki's portly girth and dimuntive stature proved divisive for the audience with many turning off shortly after the opening episodes. That he was different visually from the common Dullster McBlandypants that usually populate anime seemed reason enough to stick with it, that he was the subject of bullying is not unsurprising and perenially topical within Japan.
But of course the love interest, the aerodynamic and quietly worshipped "Snow Black", takes him figuratively and virtually under her wing in order to... Drive the plot forward? Her overtures towards Haruyuki obviously lean towards the romantic but it's left as a hanging question as to why their relationship developed to begin with. There are of course other female characters who intersect with him and run the gamut from the spikey childhood friend to the obnoxious child prodigy, even a motorbike riding maid is ham-fistedly crowbarred in.
This is after all an absurd proposition: a bevy of technologies that defy physical and biological limitations but are relegated to a small subset of Japanese youths. Why not have a harlequin and a blue Transformer attack a faceless woman with blades for hands? Why not have a red Thundercat and a Bubble Bobble dragon shooting the breeze in a virtual Akihabara bar? The ridiculousness and inventiveness in avatar design and teenage stupidity is just enough to carry the series, helped along by some wonderful tertiary characters - one missing her legs, another a foul mothed biker punk - who show there are nuggets of good ideas hidden amongst the technicolour robot menagerie.
All of that goodwill is useless though in the face of an impotent and unsatisfying second half, championed by an antagonist so dastardly he may as well be twirling a pantomime mustache and swearing at kittens every time he is on screen. So gloriously unhinged is he that a late stage attempt to humanise him falls just before he stops becoming a threat to the incompetent inner group. The same group who dramatically realised they should tell each other everything in the former half of the series, but then proceeded to not tell each other anything in the latter.
To its credit, the series writes out the thoroughly overpowered Snow Black by shipping her off to Okinawa for a pace breaking sidestory heavy with sapphic overtones. This means the "well I'm level 9" automatic-win no longer applies to Harayuki which comes dangerously close to forcing some personal development on him and revealing an underlying quest for individuality. But then she arrives to save the day anyway, all but shouting "deus ex machina!" as she swoops in on her flying black pony. This is the girl Harayuki swears he will protect despite her solving almost every problem for him thus far and being more than capable and confident on her own.
This though is perhaps missing the point to Reki Kawahara's other virtual world romp which may be deficient in many of the areas that count, but is trashy enough to slip by without too much friction and flashy enough to be entertaining when it needs it most. Battles however tend to have all the subtlety of throwing a super sentai squad and some fireworks into a washing machine and hitting "Spin", not helped by thumping techno music (KOTOKO's opening not withstanding) and primal yells from the main cast.
The good parts then - the fairy-tale leanings, the H.R. Giger-esque level designs, the out-of-body disassociation when using the "Burst Link" - are too well camouflaged by the uninspired dreck and forgotten plot threads around it. With hushed rumours of a second season in the pipeline and plenty more material from a writer who has proven a commercial success, it's still possible that Accel World will manage a net positive. More likely however it will retain the dullard approach it showed with this series: all pomp and glitz but zero depth.
1. KOTOKO got the first ED. Love that song.
2. The comparison with SAO is apt, but I would add that having the RL binary with the virtual (and again in the Brain Burst world, so essentially this story is contained in separate 3 worlds) gave Accel World a thematic balance that SAO lacks entirely. Of course, I think Accel World is significantly better in some aspects (theme and plot) as a result.