Mami Futami

A playful pair of twin sisters who make a two-girl singing sensation. Ami and Mami both enjoy doing impressions and teasing their friends, though Mami seems to somewhat be a little more mature than Ami (even though she is technically the younger one). The only way to tell the two girls apart is through their hairstyles—Ami tying her hair to the right, Mami to the left—otherwise, they are completely identical. They use this fact by switching their hairstyles and both performing as idols (underneath Ami's name). The only people privy to the fact that Ami is actually a pair of twins are the insiders of 765 Production. (Source: idolmaster.jp, Wikipedia)