|Novel||Chapter 3 The Watch/Guard On The Rhine (Vol. 1)|
|Manga||Chapter 2 Type 95 Elinium Operation Orb (Vol.1)|
|Anime||Did not appear|
Erya is a friend, classmate and roommate of Viktoriya Ivanovna Serebryakov. She is working as an artillery spotter.
She has knowledge of things that someone of her status are not supposed to know. During her first appearance she was able to tell Visha which units they will be assigned to and who Visha's commanding officer will be beforehand. It was implied that she eavesdropped on the officers.
In Plus Ultra, she was able to congratulate Visha on becoming a teacher in a letter before either Visha or Tanya knew anything about it.
She did not appear in the Anime, and all scenes and references of her were removed.