This article, Rayanone Michihofo, is property of 0 Espada.
Rayanone Michihofo is the self-proclaimed succesor of Aizen. He declares himself: El Elemento (The Element) Dictador Bronce (Dictator Bronze).
unknown but he even says it is the arrancar equivalent of Ryujin Jakka. That means the strongest zanpakuto, not the fire.