WMG / Pink Bitch Club

The colorful world is a Mental World created by Minako in order to forget that she killed Gyaruko

There is some evidence for this. In the opening, Minako is shown as a messy-haired shut-in before suddenly turning into her colorful gyaru self. For this theory, Minako was a popular Alpha Bitch and Gyaruko was her best friend who she was in love with. Gyaruko rejected her due to being straight, and Minako killed her in a fit of rage. Covering up Gyaruko's death, Minako became a depressed shut-in, creating a fake world where her favorite fictional characters, Charlotte from a popular anime (Chi no squi has a different art style than the rest of the videos), and VYT-24 from a video game (VYT-24 is based on Multi from To Heart 2), are her friends, and Gyaruko is alive and in a relationship with her.