One sunny day invaders came from space. They weren't little green men or funny girls wearing school uniforms, though. They were ugly robots which defeated the UN forces in seconds. After that the invaders (known as "eyeballs") roamed around and observed human society. In fact, they were peaceful unless attacked. They were polite and followed all the traffic laws, too. Still, they were aliens and the people of Earth wanted them to go home. The Kitanohashi High School Magic Club took it on themselves to defeat these foul robots and free the world.

[Source: Anime News Network]

A parody-esque epilogue to both Shamanic Princess and Mahou Tsukai Tai!.

As a marketing ploy back when Shamanic Princess was first released, buyers who purchased all six first edition LD's of both Shamanic Princess and Magic User's Club, and sent in their proof of purchases before a deadline received a special OVA entitled Shamanic Princess vs. Magic User's Club. It was never sold in stores and was a special omake by the series' creators to the fans. The OVA contains an epilogue to both series, which is fitting considering they both came out at the same time.

[Source: Wikipedia]

The aliens have been defeated, and the Bell has been transformed into a gigantic cherry tree. Now, the brave Magic User's Club must reconvene to deal with a new problem. Apparently, some inconsiderate persons left a skyscraper sized cherry tree in the middle of Tokyo, and it's become a major inconvenience to everyone in the city. Even though they have no idea who could have done such a thing, the Club feels strangely responsible and springs into action. Meanwhile, a mysterious person is spying on the magic club in the form of a small boy.

[Source: Anime News Network]