I covered the female Kamen Riders before, but here is an update and more extensive list. In Kamen Rider 555 (2003), many people who transform into the same armor or 'gear.' Where many men would wear one gear, one female would. One girl (Rina) wore the Delta armor but was kicked out of it a few seconds later. Both Yuri and Megumi become different versions of Kamen Rider Ixa in the Kamen Rider Kiva movie (2008).
Human Tackle (1973)
Yuriko Misaki/Electro-Wave Human Tackle is a modified human just like the titular Kamen Rider Stronger in his series. She worked a bit as Stronger's sidekick and in due course she fell in love with him. She sacrificed herself to save Shigeru from being poisoned by Doctor Kate. In Kamen Rider Spirits manga, Despite Misaki being dead, her story is continued to be told through Shigeru Jo's flashbacks of her.
Kamen Rider Femme (2002)
She is the first official female Kamen Rider. Miho Kirishim was portrayed by Natsuki Kato. She was only in the movie Kamen Rider Ryuki Episode: Final and in the costume a cameo in Kamen Rider Ryuki: 13 Riders. Her power was of the Swan.
Kamen Rider L-arc (2004)
Her true identity is Miwa Natsumi and she was portrayed by Yoko Mitsuya in the movie Kamen Rider Blade: Missing Ace and in kamen Rider Decade. "Larc", is French for "Archer." Miwa Natsumi originally applied as an office worker, but was berated by the boss. As a result, she knocked him out after having enough of his words. She was handpicked, along with two others to become the New Generation Riders for BOARD to capture the Undead released by the Albino Joker.
In the series Kamen Rider Hibiki, she appears in one episode. All the warriors had motifs of instruments, hers was a harp. Although she is in her 80's, Shuki used her power to assume a form that resemble herself in her early 30's. When she was young, her entire family was murdered by the villains. She used this as a reason to become an Oni. She used personal grudge and not the desire to uphold justice and protect the weak as a reason to fight. Unlike the others, the demon face took over her helmet. She ended up killing herself to get her revenge. She is the only Kamen Rider to ever have a skirt. She is the first female to actually be in the TV series, not a movie.
Appeared in the TV series Kamen Rider Decade, Nana Akiyama reprised her role from Hibiki and transformed into Amaki.
In Kamen Rider × Kamen Rider Double & Decade: Movie Wars 2010, the Kivat known as Kivara helped Natsumi Hikari transform into Kamen Rider Kivara. Officially she is the fifth and so far last Toei female Kamen Rider.
She is the counterpart to Kamen Rider Femme, she appeared in Kamen Rider Dragon Knight in more than just a couple of episodes. Kase, a warrior from Ventara was the romantic interest for Kamen Rider Wing Knight.
Kamen Rider Nadeshiko
She will be introduced in Kamen Rider × Kamen Rider Fourze & OOO: Movie Wars MEGAMAX (2011). She is a mysterious girl that fell from the sky and fell into Gentaro's arms and heart during Amanogawa High School's culture festival.
Kamen Rider Mage
Mayu, Medusa's twin sister changes into a rider to fight Medusa in Kamen Rider Wizard (2012-2013).
Kamen Rider Marika
She is an adversary of Kamen Rider Gaim (2013-2014). Yoko later assists Mitsuzane in a scheme to take Kouta's Sengoku Driver, deeming the plan to be faulty due to the youth's unwillingness to personally handle the deed himself. But ultimately, though she went along with it on Takatora's orders, Minato's loyalty is to Ryoma as she reports to Takatora about his younger brother's betrayal while relaying the youth's offer for a partnership to Ryoma to cover it up.
Stageshow Kamen Riders
Even though not official (stage show Riders aren't consider canon), the Alpha suit was used by a female in the Kamen Rider 555 stage show. Pictures available here in this Japanese site.
A female Oni Kamen Rider as age 23, a human with Makamou blood in her veins who brainwashed Jaki into being her slave. Mujaki use a microphone as her weapon and her name means "Illusion Snake Demon" and is synonymous with innocence.
Related: http://henshingrid.blogspot.com/2010/09/stage-show-only-kamen-riders.html | http://henshingrid.blogspot.com/2008/07/female-kamen-riders.html | http://henshingrid.blogspot.com/2009/01/gender-change-for-kamen-rider.html | http://henshingrid.blogspot.com/2010/09/human-tackle-prototype-female-kamen.html |