One of the characters I heavily want to play right now is heavily influenced by Ranma 1/2, in fact originates from a Ranma Next Gen game.
Here we go the synopsis (granted, this after she got some play and had additions to her back story from other players and GMs...things get complicated when you're not the only one with a say in your history....though the additions make for an interesting storyline)
Ranma and Akane get married (finally, can't remember if he got the curse cured or not, it never came up in game)....anyway
Kodachi decides to go on a journey about Asia to "find what was so lacking about herself that her darling Ranma would choose the loathsome Tendo girl over her" and acquires some magical items and experience along the way
Kodachi falls for some Korean guy and ends up pregnant (another player's background, hence why I'm vague on it, placing it here because the GM of game decided it came before my character's origin)
Kodachi reaches Jusenkyo and falls into Spring of Drowned Twins
Both Kodachis assume the other is a "horrendous demon set upon eliminating my glorious self in order to fit into decent society and secretly use her incredible influence to rule Japan" and start fighting.
Clone Kodachi ends up falling in Spring of Drowned Raven, since she technically IS a curse, she ends up with mixed curses instead of transformation (sort of a quicker version of how the Phoenix Tribe evolved from the various bird springs altering their DNA). Original Kodachi uses a magical device to seal Raven-Kodachi away.
Raven-Kodachi's prison (glass egg) is stolen from Kodachi who doesn't try too hard to get it back.
Kodachi acquires book of spells intended for the mortal female descendants of Hecate. (complete with ranty forward how telling Apollo "no" does not mean she's a lesbian like Apollo's sister)
Being of the right bloodline, somehow, Kodachi starts dabbling in spells dangerously. (other player's ideas here)
Kuno moves out of the mansion, think with Nabiki, and leaves it to Kodachi.
Kodachi learns the nature of the Jusenkyo twin curse and realizes that she's done something horrible to someone that might be considered her daughter/sister.
Kodachi plays around with a gate spell and opens a door under the Kuno mansion to a "hell like place" (other player's ideas here, they wanted a survival horror setting under Kuno mansion)
Kodachi is unable to close the gate completely, so it keeps popping ajar or open. Also can't grow stronger while the gate drains her. She's stagnated herself.
Kodachi starts training old "friends" (gymnastics team) and magically altering pet crocodiles to fight off the demons in the tunnels under the Kuno mansion so they don't get out.
Term "recluse" is added to "crazy/psychotic" in her reputation. Kodachi considers herself irredeemably evil, especially since her efforts to keep the gate closed are to preserve her honorable reputation rather than to save people. As well as her willingness to harm/kill innocents to keep her secret.
Kodachi realises that she's the only remaining female heir to Hecate's blood, and her brother, Kuno has only a son and thus can't use the spells (still hasn't told anyone about the hellgate). Starts looking for her daughter/sister's prison.
Determines that Raven-Kodachi is unlikely to trust her and is also likely to move down the same paths of evil she herself went down if she is allowed to keep her ego.
Raven-Kodachi's spell-trap is broken by a curious child in an antique store.
Sixteen year-old raven girl version of Kodachi released into the world.
"Karasu" (Japanese for Raven) makes a beeline for Nerima and tries to take out Kodachi. Kodachi thoroughly humiliates and torments her verbally and physically about how weak and ineffective she is. (both to encourage Karasu to hate her and destroy the ego that brought her to evil). Has servants take and deposit broken form at Ranma/Akane's doorstep.
Ranma recognizes who/what Karasu is after short interaction...confronts Kodachi, who admits the secret of her gate, calling it her insurance device to keep people from trying to make her pay for her crimes. Boasts that there's nobody with the right blood to close the gate and that even if there were, they'd need the spell book (which she no longer needs herself) to learn initially.
Predictably, Ranma steals the spell book and starts trying to train Karasu in martial arts while looking for a trainer in magical arts. Giving Karasu a mentor Kodachi considers good and setting up what Kodachi hopes is her own defeat and the elimination of the evil she has brought to the world.
fairly easy to do with Winged Human template (in 3.5), practically anything with Ritual Caster in 4e (since the necessary magic in question is ritual magic) and altering Eladrin so the racial power is fly rather than teleport....
and then there's BESM and HERO, which are point based systems capable of...well...anything
would have to change names and places in a lot of cases....