A Kamen Rider Crossover Story Beginning with Amazon

Two years ago, an experimental accident unleashed 4,000 human-devouring experimental subjects known as Amazons into this city. One late night, after the Rain God Project was put into action, a firefly Amazon invaded Nozama. Yan, who had been transformed by her older sister into a Type Four Amazon called Sigma, was awakened and sent to engage the enemy. But just as she was about to finish it off, she suddenly vanished. When she opened her eyes again, she found herself in a strange place. From the memories in her mind, she learned... she had transmigrated! Traveling between countless worlds, how will she forge a legend of her own?