: Looking back on this period, Rei has described feeling like a "robot" who had to suppress her emotions to meet the demands of the industry.

However, the pressure of maintaining the idol image took a toll. In November 2017, Rei abruptly left the group—then known as —citing disillusionment with idol culture and severe throat issues.

The Evolution of Rei Kuromiya: From Junior Idol to Rock Rebel

In 2015, at age 14, Rei joined alongside Rie Kaneko and the cross-dressing Australian wrestler Ladybeard. The group's single "Nippon Manju" became a global viral hit, blending "kawaii" aesthetics with heavy metal.