Gunka no Baltzar Gaiden: Ginkai no Jurij  

Gunkaku no Baltzar Gaiden: Ginkai no Jurij, Espionage Jurij, 軍靴のバルツァー外伝 銀灰のユーリ

"Ginkai no Jurij" is a prequel to "Gunka no Baltzar" that takes place seven years before the main story. It focuses on the lives of Jurij Geunsen and Timo Baumann.