Puella Magi Machiko Magica is an anime/comic/story that takes place in the same universe as Puella Magi Madoka Magica, and takes place as a sequel to the events in the anime. It also shares two canon characters from the show, Kyubey and Bebe.
Machiko, a girl from Tokyo, just switched schools to fit her schedule better. But while she's there, she learns there is another new student, a girl named Aina Aoki. When Machiko unintentionally stumbles in on her, she learns that she is fighting witches with magical powers granted to her by the creature Kyubey. And when the odd little space cat offers her powers in exchange for one wish too, her world turns upside down. Aina is in close combat with another magical girl who has accused her of stealing territory, and when two other magical girls, who owned the territory before anyone came along, things get even crazier.