Beruche discovered Sailor Mercury's secret identity and disguised herself as a human in order to join the local chess competition Ami was also in. Beruche and Ami defeated everyone until only two of them were left for the final chess game, where Beruche revealed her true identity. She suceeded in trapping Sailor Mercury and the others but her victory was cut short by Tuxedo Mask's intervention. Her two sisters Karaberas and Petz abandoned her, and told her it was better to leave her to die since she was a failure. This caused Beruche to lose her will to live and she started to freeze the surroundings, declaring that she was going to kill everyone, including herself.

Cooan then approached her through the ice and told Beruche she loves her, as a sister would. Beruche then asked Sailor Moon to turn her into a normal human being as well, and the two sisters were reunited.