Mirei first showed up in Digimon Masters Online Tera World Re: Digitize, that had been a Japanese-exclusive PSP game released in 2012. You play as Taigei, a 16-year-old boy who gets sucked into your digital world. Along the way, you stumble across Mirei, who's got hacked it to have two partners, an Angewomon and LadyDevimon. In typical Japanese fashion, the tale gets profoundly confusing, and which is probably one justification it never got their state run English translation. Eventually, the Nintendo 3DS version using the game, Digimon World Re: Digitize Decode, explains where Mirei Mikaguracame from. She would become a scientist working while using GIGO Company, short for Global Information Global Organization. After an experiment goes completely wrong, she ends up getting sucked from the digital world, incapable of escape. Untethered inside the physical world, she’s unengaged traveling dimensions and spends her time protecting her home plus the humans that seem to go back and go. Buy Digimon Masters Online Tera at: https://www.mmoah.com/digimon-masters-online