Anime First: Conceived originally as an anime, it had two manga adaptations. The one done by Keiko Okamoto was released as a companion to the anime, while the other one drawn by Asamiya himself was serialized around the end of the first season.
The anime had an official home release on DVD by Viz Media in 2004. If you search right, it's still possible to get some DVD's copies at very low prices from secondhand sellers... however, only 18 episodes out of 52 were released and distributed in four volumes. Of course, there are copies in the net of all the episodes... from the Latinamerican dub, mostly (that used the English translated scripts for its dub), or the Brazilian Portuguese dub, too. Don't count with any luck if you are looking for fansubs, though.
And there is Okamoto's manga adaptation. Tokyopop only released the first part of the manga and the volumes can still be obtainable from second hand sellers at very low prices. Corrector Yui Ver.2, though...?
While the series got a TV release in Latin America and Brazil in earlier 2000s, the United States didn't have the same chance. In a time where Magical Girl series as Card Captor Sakura and Sailor Moon were having a good reception with their audience, and the increase of the interest of the then new technologic elements and worlds that The Matrix explored, the series would have received a push in promotion, if it was aired in TV. Yui was also a middle school student who Jumped at the Call because she was fan of the genre itself and would have been an ideal projection of younger viewers as well. It's unfortunate that even though Viz Media decided to release the series in DVD, they didn't even complete it, being stuck before the first season climax due to low sales.
And these low sales didn't affect the anime release only, but the Okamoto's manga adaptation release, too. Tokyopop gave up the license not so long after publishing the last volume of the first series. There's no way to get Corrector Yui Ver.2 if you don't give a try in searching at Japanese auction sites. Same is also applied to Asamiya's adaptation.
In the LA dub this is much more common to find than the Japanese version. Ecco and Reiko have the same dub actress, but barely talk to each other in a scene. War Wolf and Grosser are another examples, though their dub actor manages to sound different between one and another when both appear in the same scene.
The Japanese version, however, applies Fridge Brilliance and Fridge Logic cases. Grosser and Inukai share Mugihito as their voice actor, when the viewer finds out that Inukai created Grosser at his own image - he would find him wherever he was because he was thinking alike as his own creator. Fridge Logic happens when Takashi Matsuyama started playing as War Wolf in the whole series... until the climax of the season happens, and Synchro starts talking to him via a prerecorded message to reveal he was War Wolf all along.
In one of the volumes of Asamiya's manga, the anime series planner commented about some plots that were cut due to some issues they were having when working in the animation, especially involving some ideas for networks, such as episodes based on a Mystery Net, an Arabian Net, a net based on Yui's Four Panel Theater, and a Future Net that would have involved a 'Game of Life' simulation.
Apparently, back in the day, Viz Media acquired the Kia Asamiya's manga rights to publish it in America.