magical girl; girl with magical powers; young witch
Primarily a genre term from anime, manga, and games; also used for a girl who uses magic in a story. The cross-reference 魔女っ子 refers to an older related trope.
See also: 魔女っ子
The protagonist of this anime is a magical girl.
魔法少女ものの作品が好きです。
I like works in the magical-girl genre.