I have a theory that parody on its own doesn't work. You need characters, stories and jokes, just like anything else. Parody can add a unique spice to something that's already funny and, when done right, make an audience just about die laughing, but that's only for a moment or a scene. What about a 26-episode show?

Excel Saga is the most notorious parody anime. It's mental, it's genre-hopping and it ends by becoming unbroadcastable. The whole thing's so hyperactive that you almost have to admire it whether you like it or not, but I still think it proves my theory. The first half is mediocre. Yes, I mean thirteen episodes. I'd occasionally laugh at a joke here or there and it wasn't so bad that I didn't keep watching, but as far as I could tell the show was static and pointless. Nothing was happening. There were no characters and no story. All they had was an endless round of genre parodies that weren't even particularly funny, although they had their moments.

Urusei Yatsura though took ages to get going for me too. This might be where I put forward a second theory. Give an anime production team licence to go completely batshit and, given enough episodes, they'll morph into a kind of brilliance.

The set-up of this show is that Excel is a hyperactive cretin and agent of A.C.R.O.S.S., an organisation that's trying to conquer the world. Her boss (whom she worships) is Il Palazzo and her colleague (after episode two) is Hyatt. Other characters in the show include:

You get the idea. This show isn't so much breaking the fourth wall as turning it into a rockery. There are other humans, but nothing they say or do matters in the slightest and during that first half they're all boring. The show's format is that every week, Excel and Hyatt get another mission and the show spoofs a new genre. These include alien invasion, 1980s action movies, creepy romance, crusading social journalism, horror, sleaze/fanservice, sports anime, teen drama and so on. However nothing meaningful ever happens, unless you count a minor character called Pedro appearing for a few minutes each week for his life to become even more of a nightmare. Excel will cause chaos and the closing credits will say that this week's experiment failed.

Halfway through, though, things improved. It was the Ropponmatsus who triggered it. Admittedly they don't seem universally popular, but for me at last we had some characters capable of supporting a story. Not long afterwards, the parodies really start hitting their stride, with episode 17 (Animation USA) achieving brilliance and episode 18 (Municipal Force Daitenzin) making me laugh like a drain at sentai. I don't even watch sentai! By this point they've found a craziness momentum, like the anime equivalent of freeform jazz. It's out of control, but in a good way.

Eventually we even get a story! Excel Saga is always going too far, but one episode ends with an apocalypse. The following week we're doing Fist of the North Star and A.C.R.O.S.S. is at last starting to take over the world. Things build up from there. Episode 24 is gag-free after something crushing happened to Excel, after which the final episode (25) manages to be silly and yet also briefly find the emotional power I associate with anime. Excel really does love Il Palazzo, you know.

However episode 25 was only the final episode of the TV series. Episode 26 was straight-to-video and is unbroadcastable, throwing in all the jokes the production team couldn't do on TV. Knowing that in advance, I found it less extreme than I'd expected. It's just another Excel Saga episode. It's got a storyline and everything. They even bring back Cosette from episode 8, who'd been my favourite character in that half of the show. However there's also a song and dance number, parody of the show's own opening title sequence, gratuitous shower scenes, nudity, underage nudity, torrents of blood, sexually active rabbits, erections the size of your arm and an entire story beat based around a paedophile and a nine-year-old in a love hotel. The episode's title is Going Too Far. Needless to say, it's great.

Do you need to be an expert in anime? Um... it'll help. I've watched way too much of the stuff, but even I was only getting about 25% of the jokes. There's a pop-up feature on the DVDs explaining all the references, which is interesting in an academic way and helps make the show feel less random. I laughed out loud at their takes on Sailor Moon, Fist of the North Star and Matsumoto shows, so presumably I'd have done the same if I'd been up to speed on Gundam, Dragonball and so on.

Then there are the actors. I don't normally notice voice acting, but Kotono Mitsuishi (Usagi in Sailor Moon) is giving one of the all-time "demolish the recording booth" performances as Excel. She'd blast out her lines so fast that they had to write additional material for her, while Jessica Calvello killed her voice trying to keep pace with her in the English dub and had to be replaced halfway through by Larissa Wolcott.

At the very least, its attitude to life, death and storytelling makes it unique. The Great Will of the Macrocosm allows Hyatt's main character note to be "dies frequently", for instance.

Is this a good show? That's hard. Years ago, when first getting into anime, I watched the first episode of this on VHS and it didn't make me want to watch any more. Similarly at the halfway point, my judgement was that the ongoing story was a waste of time, the protagonists were one-dimensional and the supporting characters felt like walk-ons who'd never walked off. Furthermore the anime for some reason was spending time on these things, even though I didn't care what anyone was doing and everything was too random to have a direction. However I kept going and in the end was impressed, having been won over by the show's manic energy and willingness to go too far. You can't say it lacks personality.

There's also an OVA spin-off, Puni Puni Poemy, which was banned in New Zealand for being even more offensive than Episode 26. I'll be watching that, then.