The Contract Bracelets are used by the Kämpfers (German for "fighter").The Contract Bracelets are connected to the person's abilities and personalities. Some Kämpfers can change personalities such as Akane Mishima. The Contract Bracelets also can be controlled by the person who wears it (such as Akane Mishima, Senō Natsuru and Sangō Shiziku). The Contract Bracelets have 3 color in the anime series. Blue, Red and White. The Blue Contract Bracelets, The Red Contract Bracelets and the White Contract Bracelets has the same properties (Transforming a person into a Kämpfer). When a boy has a Contract Bracelet and transformed into a Kämpfer, they will be switched to a girl. Kämpfers has to be a female so even boys can become Kämpfers. The Contract Bracelets has many mysterious powers as well.