From Yen Press:

Mami's warm personality has made it difficult for her to adjust to her solitary life as a magical girl, where survival often takes precedence over kindness. When she meets Kyouko Sakura, a fellow lone wolf, she is excited at the prospect of working together with another magical girl and forging a friendship built on ultimate trust. But many are the sacrifices all magical girls must make, and the consequences of Kyouko's choice are only just becoming clear to her. When the pain becomes unbearable, will Kyouko remain standing beside Mami as a force for the greater good...?