Fantasy Zone: Boss no Gyakushuu is a mobile phone game released for i-mode 503i devices through the Sonic Cafe portal. It is a boss rush game, where Opa-Opa battles the bosses from the original Fantasy Zone.

Fantasy Zone: Boss no Gyakushuu is a mobile phone game released for i-mode 503i devices through the Sonic Cafe portal. It is a boss rush game, where Opa-Opa battles the bosses from the original Fantasy Zone.