Mii

about:

The baby sister of the three sisters, Mii is a hyper-energetic social butterfly, quick to make friends or help out those who are distressed. She undertakes her more serious aid missions while cosplaying as Magical Girl Mii, who supposedly wields a host of typical powers, but in actuality is only capable of exceptional feats of healing. Mii remains largely oblivious to her limitations, however, and continues to "use" her non-functional abilities in defense of the common good.