Mami is the top Gyaru of Ikebukuro, the "Queen of Ikebukuro". She sees Ran as a rival and is occasionally jealous of her. When filled with jealousy, she will usually challenge Ran and the two will compete. In the anime, she's a debutante leading a double life as a Gyaru.

Later on in the series, Mami falls in love with Yuya and the two become a couple.

She also develops a truce with Ran in Volume 5 of GALS! 'It's okay to have a change of heart'.