The old Mothra may be dead, but a new Mothra has arrived! After rescuing a Mothra egg from the Cretaceous period, Mira and Emi arrived back in the present... or, actually, back at Mothra's original fight against Antra. And worse-they brought Meganulon with them! Is it possible that their actions in the past are what led to Mothra's original death?! Whatever the case may be, Mira and Emi now have a baby Mothra larva that they have to train to one day prevail against Antra and the monstrous Meganulon... or else this dystopian world of their own making will never be undone.