In episode 16 there is a possible suggestion that she is the winged dog creature or a reincarnation of the being that is seen during certain flashbacks of the incident where Apollonius tears his wings off to save Celiane from the Shadow Angels. One such flashback takes place in episode 12 where a small dog with wings is seen flying to Apollonius' back while whining after he tears off his wings to block Moroha's blade from hitting Celiane. The same winged creature is also seen floating and looking at Apollonius before he tears himself from the cross. In episode 16 when Apollo is calling Rena there is a quick scene of a dog with wings atop a green mountain with howls echoing both during and after Apollo screams her name a couple of times. Rena states (in the English dubbed version) "He Calls" after a vision of Apollo changing into Apollonius and then teleports to him inside his Vector. When she asks him why he isn't afraid during the conversation that follows he states (again in the English dubbed version) "What like I don't know you?" and then rubs his nose.
Seiyuu: Satou Hiromi