Mami - a senpai and mentorKyouko was under attack by a powerful witch, when all of a sudden another magical girl came to her aid. The two worked together to defeat the witch. We find out that Kyouko had been chasing the witch because it was the first one she ever fought, and lost to, when she first became a magical girl. Mami introduces herself, and shares the grief seed with Kyouko, because it was her battle too. This shocks Kyouko to see another person sharing with her, but she accepts. Mami invites Kyouko over for lunch. She makes peach pie and other goodies, all of which Kyouko loves and devours down, drool at each bite.
Kyouko acknowledges that Mami is a better fighter than her because she is able to analyze and fight smartly, making her reliable in battle. Kyouko asks Mami if she would allow her to be her apprentice for awhile so that she can become a better magical girl. Mami declines the apprentice positions, but says she would like a magical girl as a friend instead. The two smile and agree to work together on defeating witches in the area and also to be friends outside of battle. Kyouko asks Mami if she is getting in the way of her work, or holding her back. Mami says of course not, and that she enjoys the company of Kyouko. Mami asks Kyouko to come by anytime and help her fight or see her.
The next time the two fight a battle together, Kyouko asks Mami to come back to her house with her so that she can show some hospitality, too. Kyouko's parents tease her by telling Mami that she is the first friend Kyouko has ever brought home with her. Kyouko gets embarrassed, but Mami seems thrilled to learn that she is the first. The two bond over their similar ideals on fighting and what type of magical girls they want to be. They both have goals and passions, which make them an ideal match.
Time goes on, and Kyouko stops showing up. Mami begins to sadden, thinking she just lost a friend. She hears on the news about how Kyouko's family church was burned down, and that people were dead. She rushes to Kyouko and apologizes for not coming sooner. She tells Kyouko that she failed her as a senpai, but she promises its going to be alright and gives Kyouko a huge hug. Kyouko tells her she lost her powers, and that she will be a bother in battle for Mami. Mami promises that she can protect her and that she doesn't mind it at all, but Kyouko seems bothered by that thought. The two end up crying together on the ground and continue to hug for sometime.
Kyouko loses herself in her own misery, and tells Mami she is no longer going to be the person to help save the world with her. She doesn't see the point in killing familiars anymore because its just a hassle. All she wants to do is get by and survive, not save anyone or anything ever again. Kyouko tells her she has to leave because they have opposing views, and Mami grabs onto her arms. She cries out that she can't let Kyouko be alone to suffer, "I can't let you be alone!" Kyouko tells her to get off of her because her mind is made up. The two end up physically fighting because words can't solve their altercations. Both of them are head-strong and don't want to give up on their own thoughts and beliefs. The two end up separating because they can't agree in the end. Mami tells her she is hurt because she thought that she finally found a magical girl who shared the same thoughts and dreams as she did. When Kyouko is by herself after she leaves, she says, "You'll find some great friends," in a genuine tone, hoping that someone else could make Mami happy because she no longer can live for anyone else but herself.
Later on, Mami and Kyouko run into each other again. Kyouko stays cold towards Mami, but deep down she actually cares for her. When Mami gets injured in a battle, Kyouko screams out to Sayakato take care of her friend, "do you want her to die??" This shows that although Kyouko tries to live a selfish life so that no one can hurt her, she can't do it. She wants people to be happy, that's why she made her wish in the first place. Although Mami definitely cared more for Kyouko in the beginning, especially because Mami was desperate to be understood and find a friend, Kyouko still loved her as well.
Mami's grief seed becomes darkened because she begins to give up on life. Kyouko fights her to prove to her that life is worth living and to try to get her to listen to her about not giving up on herself. Kyouko ends up telling Mami the truth, that the only reason she didn't fall into being a witch and have a black grief-seed was because of Mami. Mami was the one light in her life that kept her sane, and kept her head strong enough to push forward. She became selfish and ran away instead of staying by Mami's side. Mami falls to the ground, beaten by Kyouko. She is impressed that the one she trained finally beat her. Kyouko holds onto her hand and tells her that she is the only family she has left, and that she is more than just a friend to her. Kyouko has to leave to go save Sayaka, but Mami doesn't want her to go. Mami tells her to promise her that one she comes back "that [Kyouko] will never leave [her] again. Sisters shouldn't worry one another." Unfortunately, Kyouko comes back basically defeated and uses the grief seed that she got from Sayaka's witch to purify Mami's grief seed so that she can live on. Kyouko ends up sacrificing her life to save Mami in the end. She smiles because in the end, she saved at least one part of her family: Mami.