|First appearance||Episode 1|
|Voiced by||Aya Endou|
|Rank||Second Lieutenant (少尉)|
Filicia Heideman joined the Helvetian Army at a young age. She was originally assigned to 1147th Platoon. Sadly, she was the only survivor when an enemy tank destroyed her tank during the Battle of Vingt. She was later rescued by Princess Illya, who led reinforcements. Eventually, she was promoted and given command of the 1121st Platoon.
She is currently the commanding officer of 1121st Platoon of the Helvetian Army, which is stationed at Clocktower Fortress near the town of Seize. Because her unit is assigned in a remote outpost, she is lax on ranks and regulations.
- The unit's commanding officer, who does away with ranks in her unit, preferring everyone to be on a first name basis.
- She is self-conscious of her body.
- She is afraid of lightning.
- Suffers from PTSD due to being the sole survivor in a battle several years ago. Saw her Platoon being wiped out right in front of her.
- Was trapped in a Subway Station and talked to a dead old era Soldier (Unclear whether it was a hallucination or a ghost, although the flashback of the old era soldier was a real event).
- In ep07, Rio says that Filicia was “on the front lines at the battle at Vingt-et-Un.
- At the end of episode 12, Filicia was promoted to Commander evidently when Rio addresses her as Commander when Rio returns to Seize.
- Her promotion is most likely an acknowledgment for leading the 1121st Platoon against the Helvetian Army at the risk of a court martial on the charge of treason to delay both armies from fighting in order to buy time for Rio and her troops to arrive and officially announce the war was over.
- Behaving like a motherly figure and making the platoon member happy so they will live the last times of their life in happiness.
- She, Noël, Naomi and Rio are bootleggers, manufacturing alcohol illegally.