A Magical Girl (Japanese 魔法少女 - mahō shōjo) is a prototypical character from girl's (shoujo) anime and manga, entailing a whole genre of her own, the magical-girl genre, which is rife with recurring features and clichés. Broadly speaking, she is a young woman, with unusual powers, and usually with some secrets.
The genre began in 1966 with the series "Mahoutsukai Sally" a.k.a. "Little Witch Sally", inspired in turn by the US TV series, "Bewitched". Sally was a witch in training visiting from a magical world, who was sent to learn about Earth. Subsequent series branched out into many variations of the theme, creating sub-genres around different plots and situations.
Some variations (not mutually exclusive), with example anime series, are:
- visitor from another world: "Mahoutsukai Sally" (1966), "Mahou no Princess Minky Momo" / "Magical Princess Minki Momo" (1981)
- girl becomes an idol: "Mahou no Tenshi Creamy Mami" / "Magical Angel Creamy Mami" (1983), "Maho no Stage Fancy Lala" / "Magical Stage Fancy Lana" (1998), "Full Moon Wo Sagashite" (2002)
- girl(s) fighting evil to save the world: "Bishoujo Senshi Sailor Moon" (1992), "Nurse Angel Ririka SOS" (1995), "Wedding Peach" (1995), "Figure 17" (2001)
- mysterious thief: (a small sub-genre that owns as much to detective fiction): "Kaitou Saint Tail" / "Master Thief Saint Tail" (1995), "Kamikazi Kaitou Jeanne" (1999)
- slice-of-life stories (with magic mostly used to solve everyday problems): "Akko-chan no Himitsu"/"Akko-chan's Secret" (1969), "Himichan no Ribon"/"Himichan's Ribbon" (1993)
Sailor Moon, derived from the Codename Wa Sailor V manga, was a particularly successful franchise which combined the idea of a girl fighting evil with the color-coded fighting team. Sailor Moon ran for 200 episodes in animation, 49 episodes in live action, and had several movies. The Sailor V manga lasted for 15 chapters over 3 volumes, and the Sailor Moon manga consists of 52 chapters in 18 volumes.
Within the girl-fighting-evil sub-genre, the Magical Girl typically is a school-age girl who possesses supernatural powers that she uses to combat evil foes. An inconspicuous, regular student by day, her magical persona emerges off-hours, often at night. In many cases, this is an actual physical transformation (Japanese 変身 - henshin) which is accompanied by spectacular visual effects, music, and the girl declaiming her trademark line. The mundane and the "magical" appearance and personality can differ considerably. The magical powers are frequently associated with artifacts (e.g. jewelery that the girl wears) and talking pets that offer insights.
While Magical Girls seem to be a modern development, there are cultural similaries in Japanese history and fiction with the figure of the Miko (巫女).
In Megatokyo, Meimi is known to be a Magical Girl. The most important, though possibly biased, source of information on Magical Girls is Junpei, who considers Magical Girls to be "as dangerous as most skilled Ninja," most likely because their activities lead to "many disaster and much destruction of urban area."
(The character of Meimi is widely thought to be a homage by Fred to the "Saint Tail" series, though some details differ. This puts her in the "Mysterious Thief" category. And there isn't much written about what happens to magical girls when they grow up.)
There is no uniformity as to whether being a Magical Girl runs in families. However, the mother of "Saint Tail" was a reformed thief. So, there may be interesting questions as to how Yuki might follow in her parents' footsteps.
Considering the business-like fashion in which much activity seems to be conducted in Megatokyo, it is reasonable to believe that Magical Girls may be a well-organized, professional public service similar to "Ninja Corporation." There is no positive evidence for that, however.