Of the 9 Heisei Phase 1-era showsnote Kamen Rider Decade is lumped into the Heisei Phase 2-era series, Ryuki made the most in terms of toy sales, earning 13.9 billion yen.
Kamen Rider Femme from the Episode Final movie is Kamen Rider's first official female Rider in the franchise.
Trope-Related Trivia
Actor Allusion: Keiichi Wada plays the original Ryuki in 13 Riders. He is famous for playing Ryou, the Red Ranger in Gosei Sentai Dairanger, who also had a red Asian dragon at his command.
Actor-Inspired Element: Shinji's Hot-Blooded character as a whole started through Ryuki's Blank Form scene where his sword snapped into half. The scene where Ryuki reacted with shock was an ad lib by suit actor Seiji Takaiwa to emphasize Blank Form's New Meat status, but it was also a coincidence that the crew members hadn't thought of what kind of character should Shinji be, hence it was decided to portray him as a hot blooded fool in contrast to Ren's experienced protagonist.
Comic-Book Adaptation: Hong Kong manhwa magazine Co-Co! had produced a manhwa adaptation of the series, with the plot mainly centered around the 13 Riders spinoff film.
Follow the Leader: Ryuki's use of multiple Riders expands upon the success of Agito.
Orphaned Reference: Asakura was written to be a Serial Killer on death row, only for Executive Meddling to have all explicit references to this cut due to finding the idea too dark for the young audience. It's obvious watching however that this was the original intent as, beyond just Asakura's general disposition and his backstory having him kill his parents when he was 13, he's shown to be in solitary confinement and under heavy supervision while in prison, something which only makes sense for someone who is judged to be an active threat to society. This fact also makes his obsession with Kitaoka make considerably more sense.
Prop Recycling: The story arc where Gai debuts involves students killing each other while wearing masks that belonged to the Mooks from Jikuu Senshi Spielban. Western viewers will recognize them as the Skugs from VR Troopers.
Shinichiro Shirakura had proposed humans using cards to form contracts with monsters a year earlier, for what would become Agito.
During pre-production, there were originally 50 Kamen Riders-of-the-week planned for the main Rider to confront, each with their own Contract Beast. That number, however, was considered excessive, so it was cut to 13.
What ultimately became Ryuki was not always going to be a Kamen Rider, the plan being to end with Agito. One proposal was a knight hero based on "Cross Fire", one of the original plans for the first Kamen Rider, potentially as a revival of the Metal Heroes franchise. When the 9/11 terrorist attacks occurred, it was decided to continue the franchise so kids would have a show to teach them about justice.
Even when the setting of 13 Riders was settled, it was uncertain that all of them would appear. For instance, Ouja would have been introduced as having defeated two Riders off-screen, before things changed so that Gai and Raia could materialize in the show proper.
Two unused Rider forms exist: Raia Survive, and a form that (presumably) Yuichi Sato would've transformed into had he contracted with Guldthunder like Shiro intendednote whether he was supposed to become a Rider originally or this was just produced for the sake of "What if" is unknown. The unused Rider's name, coincidentally, was Blade, predating the series of the same name by around 2 years.
Tamotsu Shinohara designed additional Mirror Monsters Begazelle and Igazelle, both whom ultimately did not appear.
so kids would have a show to teach them about justice.