The Japanese company Sanrio is best known for its wildly popular Hello Kitty character, and the globally famous cat has starred in many animations from around the world, including several anime. Sanrio has also made several anime that include elements of the magical girl genre, including Onegai My Melody, Jewelpet, Show by Rock!! and Mewkledreamy. It might seem strange that Sanrio has never marketed a magical girl version of Hello Kitty, but the truth is that they have -- it's just become almost completely lost.
At some point in the mid-2000s, Sanrio created Magical Girl Rion-chan, a multimedia collaboration between Japan and China. The franchise revolved around three girls, Rion, Kanna and Minamo, who are in a band and gain the ability from a magical Hello Kitty plush to transform. Rion's magical girl design is based on Hello Kitty, Kanna's is based on the penguin character Badtz-Maru and Minamo's is based on the dog Cinnamoroll. Images have also been found that include a fourth magical girl based on Hello Kitty's sister Mimmy, as well as characters who appear to be villains. From these images, it can be assumed that the magical girls of Rion-chan fought the forces of evil in addition to being magical idols.
Rion-chan was meant to be both an anime and a manga, but only the manga, which was published in China in 2010, has been conclusively proven to exist, with several photos and magazine covers available online. Garage kit figures were also produced for each of the three main girls and shown at Wonder Festival, an annual figure exhibition in Tokyo. These figures don't appear to have ever been for sale, but despite their rarity, multiple photos exist of each one, seemingly all from the exhibition.
What became of the promised Rion-chan anime is a mystery. There are no episodes available online, and only two clips have surfaced on YouTube. These clips supposedly depict the beginning of the anime's opening and the transformations of the three main characters, but the quality of the CG animation is somewhat crude, and the clips don't appear to be television-ready. In fact, artist Rei Azusa, who worked on the Rion-chan franchise, has claimed on Twitter that these clips are only samples and that a full anime was never made. Since the series was backed by a company as large as Sanrio and already had a manga released and official products made, it seems odd that the anime was never completed.
Whatever factors caused the Rion-chan anime to be abandoned are unknown -- perhaps the manga wasn't popular enough, or maybe an investor pulled out of the project. It could also be that Rion-chan was simply ahead of its time -- lately, the magical girl genre has been experiencing a resurgence, with several classic titles being revived and Sanrio's own Mewkledreamy receiving a second year-long season. Sanrio would even revisit the concept of a crime-fighting musician-turned-catgirl in 2015's Show by Rock!!. Perhaps Magical Girl Rion-chan would have been more successful if it had been pitched just a little later. However, it's unlikely the project will ever be revived, so most of the details of Rion-chan will remain a mystery for the foreseeable future.