He appears before Koizumi Hana and Yukimura Ami and shoots a Shard of Darkness into Ami's neck and turns her into a scientist Hidoi. Hana noticed that Ami needs saving and is told by Bloom to transform. She becomes Cure Tulip and battles the Hidoi and defeats it with Spring Flower Attack. Frustrated, Stone leaves.
He is cruel, mean and short-tempered, with a heart made of stone. He doesn't care if the people around him are in despair, and he wants to make everyone fall in despair.
Like the other members of the Dusk Trio, Stone has the power to turn any human into a Hidoi by saying "Come forth, Hidoi, and release the evil in your heart!"