My theory is this: Rumi was probably the one in charge of CHAM's stage costumes. And the costumes were either a cute dress or other childlike outfits that fits the "innocent" profile of the idol group. As the movie progresses, the events slowly come together and make sense of what was going on with Mima (internally and externally) as she loses her grip on reality and who she was. Meanwhile, Me-Mania (Mamoru Uchida) was taking his duty as a bodyguard a little too far because he was willing to do anything for his "Mima-rin". For Example, the Mima's Room website, The exploding fan letter, The Hit-and-Run incident involving one of the delinquents, and The murder of the screenwriter, the photographer, & Mr. Tadakoro. But Me-Mania was merely a pawn being taken advantage of by his fantasy of Mima, who turned out to be Rumi herself.