Isara Gunther features as a supporting character in the OVA "Senjō no Valkyria 3: Ta ga Tame no Jūsō". She is the adopted sister of Welkin Gunther and serves in the Gallian Militia's Squad 7. Her Darcsen heritage leads to widespread discrimination, a challenge she faces with resilience.

Injured during the OVA's events, Isara encounters the penal unit known as the Nameless. She reveals Squad 7 is retreating from a failed raid and urgently requests the Nameless' aid to save them, despite Gallia labeling the unit traitors. This demonstrates her dedication to her squad and willingness to seek help from unlikely allies.

Isara acts as Squad 7's tank driver and mechanic, displaying engineering expertise inherited from her biological father, Theimer. Related media acknowledges her technical skills contributed to upgrading the weapon "Vár" used by the Nameless member Imca. Subsequent events prevented Imca from expressing gratitude for this assistance.

Her character remains consistent: calm, principled, and steadfast in defending her Darcsen identity. She wears her traditional Darcsen shawl even in uniform, reflecting pride in her heritage. The OVA's timeline places her involvement shortly before her death during the August 23, 1935 Battle of Marberry Shore, a date documented across multiple sources.