Let's be honest here: Saiyuki's story is that of Buddhist monk Genjo Sanzo going on a journey with three half-demons (Son Goku, Sha Gojyo, & Cho Hakkai) in order to stop the potential resurrection of the evil Gyumaoh/Ox King by his wife, Gyokumen Koushu, which has caused the demons of Shangri-La to go crazy & break the peace they shared with humans. That story is so basic that it essentially doesn't just leave the door open for "filler" to enter... There isn't even a door installed! Because of that, across those 101 total episodes that aired on TV, only 36 are actually adapted from the original manga & it's first sequel, Saiyuki Reload (currently, the series is on its third, & final, manga: Saiyuki Reload Blast); please note that I am not counting the small bits of spin-off manga Saiyuki Gaiden that are adapted in the first TV series, nor am I counting the second half of Reload Gunlock, which is merely based on the second major story arc of the Reload manga, but is otherwise completely different. Yes, utilizing the Saiyuki Wiki I actually counted how many episodes weren't "filler", and the total isn't even half! Anyway, I'm starting to ramble, so let's get back on track.
Though it isn't technically a "pilot", there is a Saiyuki anime that predates the original TV series. It was released in mid-1999, and is simply titled Saiyuki; though I am not sure where it came from, fans have come to call this two-episode OVA Saiyuki Premium, I'm guessing mainly to differentiate it from the TV series. While Studio Pierrot has generally done every Saiyuki anime, there are two entries that they didn't do: 2011's Saiyuki Gaiden, which was animated by Anpro & was even licensed by Sentai Filmworks a year ago (remember that?), and this "Premium" OVA, which was done by Tokyo Kids. Even though it isn't a pilot, per se, it does feature a 99% different cast than the later TV series, but is it worth checking out for those of you who love watching the hijinks of the Sanzo Party?
The Sanzo Party is hanging out at a bar in a small town located in an area that's known for its fireworks festival the next day, eating & drinking to their fullest. Unfortunately, the happy mood is ruined by a trio of demons, who make trouble with the Sanzo Party but then run after realizing who they were fighting. The next day the four leave the town and while driving their radio is hacked into by a mysterious person, who tells them to look behind them for the "fireworks show"... They then see the city blown to smithereens. Heading back the four locate the only two survivors, a girl named Mifa & her grandmother, before getting attacked by the trio of demons & their boss: Ensui, a crazed explosives expert who was sent to kill the Sanzo Party by Gyokumen Koushu. After fighting off Ensui's goons Mifa finds out that Goku, Gojyo, & Hakkai are demons and blames the death & destruction on them, telling them to leave. Unfortunately, Ensui has rigged Jeep, the small white dragon that turns into the jeep the four travel on, with a bomb that will explode in six hours, and only Ensui can disarm the bomb; also, Ensui is threatening to destroy the next town over, which is where Mifa & her gradmother are headed. It might seem hopeless, but the Sanzo Party has to rescue the other town, Mifa, & Jeep... All the while trying not to get themselves killed.
Just to get it out of the way, this story is not in the original manga, so this is yet another "filler". Luckily, though, the story this OVA tells is actually really good, and that is likely because Kazuya Minekura herself apparently supervised the creation of this OVA, which lends a sense of canonicity to the whole thing and that's only a good thing; Minekura would later also help design the main villain of the "filler" story arc that comprises the entire second half of the first TV series. Interestingly enough, this OVA gives Jeep more focus in a story than he ever gets in the entire manga, and I have to give credit for that. Ensui is an entertainingly maniacal villain, with his cackling laugh, occasional use of Engrish, & love of things that go "BOOM". Hell, even the method the Sanzo Party uses to potentially save Jeep is absolutely brilliant in its simplicity ("We're all gonna die? Then let's drink up!"). And, to top it all off, Ensui even summons a gigantic, fire-spewing beetle to help ravage the second town, all the while he continually launches fireworks to keep up the festival mood. If there's one main reason to watch this OVA, it's for Ensui.
That said, there are some flaws in the story. While Mifa's anger at the Sanzo Party makes sense, her insistence on hating them when they are obviously trying to help everyone out just comes off as her being stupid, though the OVA itself seemed to recognize this near the end when Mifa's grandmother slaps Mifa in the face for being so stubbornly hateful, so I can't complain too much. The bigger issue with the story is the inclusion of Kougaiji & his gang, specifically Yaone (a healer), which in the main story work for Gyokumen Koushu (Kougaiji being Gyumaoh's son & Gyokumen's stepson) and act as the rival group for the Sanzo Party. I can understand including Kougaiji & Yaone for the sake of pleasing fans who wanted to see them animated for the first time, but overall Kougaiji's inclusion is pretty weak & Yaone, while doing a little more in the story, also ends up as being mostly unneeded when you consider everything. But, overall, these flaws don't really detract too much, leaving the story really enjoyable in the end.
The first TV series is pretty infamous for utilizing some obvious cost-cutting measures in some moments, like long panning shots & minimal animation, but the OVA really makes the TV series' limited-animation moments look really nice in comparison. Granted, there are some really nice bits of animation in the OVA as well, but otherwise the animation definitely gives off a low to below-average budget feel here, which isn't too surprising as Tokyo Kids is generally known as a studio that assists in productions, with them having very few productions of their own. Still, the OVA does maintain Minekura's sleek & stylish character designs & the moments that do animate well can impress in the end, so overall the animation can be considered a mixed bag.
The OVA is directed by Takashi Sogabe, whose only other directorial experience seems to be the Twin Signal OVA, and overall the title does give a feeling that, while enjoyable in its own right, it could have been just a little bit better. The music is done by Yuriko Nakamura, of Ayatsuri Sakon fame, and her songs do fit in nicely with the series, but overall there isn't anything memorable musically in this OVA, a problem that does get fixed somewhat with the TV series. As I said earlier, the cast here is 99% different from the TV series, with the sole person going on to reprise his role in the series being Akira Ishida (Chrono in Chrono Crusade, Judeau in Berserk TV, & Katsura in Gintama), who voices Hakkai. It's easy to see why Ishida ended up reprising the role in the TV series, because his soft-spoken demeanor just fits Hakkai's character perfectly. The rest of the main characters, on the other hand, do an admirable job, but their replacements just better them in every way. Gojyo is voiced by Kouichi Yamadera (Kenshiro in Fist of the Blue Sky, Kaji in Evangelion TV, Spike in Cowboy Bebop), and though his gruff voice does fit Gojyo nicely, Yamadera's performance just can't match that of Hiroaki Hirata. Goku is voiced by Kousuke Okano (Kenzaki in Manga DVD Ring ni Kakero, Recca in Flame of Recca), and hearing Okano's deeper-voiced Goku really just shows that Souichiro Hoshi's later, high-pitched performance just fits the character better; Okano does a good job, but it just isn't the type of voice that Goku should have had. Finally, Wataru Takagi voices Sanzo, & Takagi probably does the best job of these three, though Toshihiko Seki's later performance wins out by a hair. Ensui is voiced by Shinichiro Miki, and he just delivers an extremely fun performance for the crazed bomber.
The Saiyuki "Premium" OVA is a neat first attempt at adapting the manga of the same name, but for everything it does really well (a fun story, entertainingly crazed villain, & surprising focus on Jeep) there's a problem right there to go with it (a stupid girl, needlessly-used rivals, some poor animation, & a miscast here & there). Overall, it's an okay entry in the Saiyuki anime series, but it easily could have been better. If you're a fan of the series I say it's worth hunting down as it is fully fansubbed, but if you're a newcomer to the series I say just check out the TV series or read the manga.