Characters from Sound of the Sky: the members of the Republic of Helvetia 1121st Tank Platoon, and supporting characters from the town of Seize and beyond.
Protagonist of the series, Kanata joined the military to learn how to play the trumpet and was assigned to the 1121st Platoon as a bugler. A cheerful and optimistic person, her presence helped to lighten the mood within the platoon.
- A-Cup Angst: It only comes up in one scene, but Kanata is aware of Rio and Filicia's assets.
- A Minor Kidroduction: We first meet her as a little kid in a flashback to the time she met a certain bugler.
- Badass Unintentional: Kanata just wanted to learn to play the trumpet.
- Country Mouse: Kanata comes from a particularly remote and backwards part of Helvetia, where old Japanese customs are stronger.
- Desperately Looking for a Purpose in Life: Bugle mastered, Kanata spends the second OVA wondering what she should do now.
- Dreadful Musician: Starts off as one, but finally figures out how to blow in episode 5. She still can't hold a candle to Rio's jazz trumpet, though.
- Drives Like Crazy: By the second OVA she's already driving the platoon's jeep. Although she drives slowly, she gets distracted easily.
- Epic Hail: She has to tell both armies the peace treaty has been signed.
- Hair Decorations: A single clip on her left temple.
- Exact Words:Rio: [...] So make as many problems for me as you'd like. I did the same[...]
Kanata: Understood, ma'am! From now on, I'll make as many problems for you as I can!
- Fashionable Asymmetry: Her haircut, with a single tress hanging.
- Hairstyle Inertia: As seen in the flashback to the time she met Princess Iliya.
- Informed Flaw: Kanata claims to get lost a lot. She gets lost exactly twice, both cases shown in the first episode. She does, however, get easily distracted, and is prone to wandering off her path if something catches her eye.
- Meaningful Name: Her given name is written with kanji that mean 'the other side', 'distant' or 'over there'. In episode 13, she declares that she'll go with Rio to find the promised land at the other end of the world.
- Shaggy Search Technique: Kanata has a knack for stumbling upon interesting things, be it ancient diaries, automated watchposts or giant winged skeletons.
- Super Senses: Her hearing. It starts as perfect pitch, and then heads into the "no one could have heard that" territory.
- You Are Better Than You Think You Are: What her senpai Rio told her in episode three when she worried about being useless.
- You Were Trying Too Hard: Episode four shows how she can improve her trumpet technique following advice from a glassblower: don't overdo it.
Second-in-command of the 1121st Platoon, Rio appears as a cool and unflappable person with a no-nonsense attitude and can be very strict in demanding military discipline and issuing orders. However, she also cares a lot about her fellow members, which makes her greatly admired by the younger members, especially Kureha.
- Achilles in His Tent: The first arc of the series is Rio mulling over whether to keep ignoring the family that snubbed her for years and keep her freedom or give in, get into an arranged marriage and stop a war.
- Arranged Marriage: To the enemy Emperor, in order to unite the two nations.
- Big Damn Heroes: In the series finale, she arrives with a peace treaty and ends the war just as the others were about to get attacked by two armies on both sides.
- Epic Hail: Good thing Kanata has Super Senses.
- Expy: Of Chihaya Kisaragi from The iDOLM@STER.
- Hairstyle Inertia: As seen in the flashbacks to her childhood, Rio has kept the same Hime Cut for years.
- Heroic Bastard: An illegitimate child of the Arkadia royal family.
- Hime Cut: Somewhat unkempt.
- Hot-Blooded: Rio doesn't do things half-assed, from giving speeches to cooking.
- King Incognito: She is an Arkadian Princess acting as a mere sergeant major.
- Lethal Chef: Bits of the kitchen turn up as ingredients of her cooking, so Kanata doesn't take her offer to help her in the kitchen in episode 8.
- Memento Macguffin: A jingle bell inherited from her older half sister.
- Missing Mom: Her mom died at an early age, as seen in episode three's flashback.
- Mixed Ancestry: Rio is of mixed heritage, since she lacks the Phenotype Stereotype looks of her blonde, green-eyed half-sister, and her last names are Japanese/Greek.
- Multiethnic Name: Rio Kazumiya Arkadia, her true name.
- Parental Abandonment: Her father ignored her for years until her older sister died and he needed a princess, any princess, to marry away.
- Rebellious Princess: Being elevated to princess status just to be politically married, Rio isn't too keen in adopting her new station.
The designated gunner of the 1121st Platoon, Kureha is also the youngest member in the platoon. However, she is perhaps the most serious member and is a stickler for military regulations. Greatly admires Rio and Major Klaus.
- A-Cup Angst: She looked a little displeased when Kanata briefly looked at Rio's and Filicia's breasts, but not hers.
- Cry Cute: She drops her professional facade and lets out the waterworks when the rest of the crew decides to go AWOL and stop Hopkins plan to reignite the war with Rome. She goes with it, of course.
- Deceased Parents Are the Best: Kureha loves to talk about her parents - although she barely remembers them.
- Girls Love Stuffed Animals: She sleeps with a lederhosen-clad teddy bear.
- Girlish Pigtails: Her usual hairstyle (tied with red ribbons) except while wearing her helmet.
- Green-Eyed Monster: At first, Kureha resents Kanata for getting some of Rio's attention as the newbie. She warms up later on.
- Military Brat: Her father was a tank commander, and her mother a military nurse.
- Never Gets Drunk: The only girl sober at the end of the first OVA. She even lampshades this as she desperately tries to get drunk and fails. She still gets a hangover, though.
- Only Sane Employee: Kureha is the only member of the 1121st that thinks there's something wrong with Filicia's relaxed approach to command.
- Straight Man: Not only is Kureha generally the most serious of the five (barring Noel's kuudere-ness), she's also literally straighter as the only person living in the Clocktower Fortress with (comparatively) few Les Yay scenes.
- Tsundere: She might act tough and professional, and seems to resent Kanata, but she's actually a softie. "I-It's not like I did it for you or anything like that..."
- With Due Respect: She's the most military-minded of the crew, pulling rank on Kanata during the second episode on their tour through the base. When Filicia decides to hide Aisha, the enemy soldier, she properly objects.
The designated driver and mechanic of the 1121st Platoon, Noël is a taciturn and reserved person who spends much of her time tinkering at the platoon's tank Takemikazuchi.
- Ambiguously Lesbian: Aisha and her become very close. In Episode 13, she also states that her wish is for "a lovely wife."
- The crunchyroll translation has it as "to be a lovely bride," which doesn't help determine orientation at all. But it does surprise the others in the scene.
- The Atoner: Encouraged by Yumina to make up for her role in the Invisible Reaper plague, she pilots the Takemikazuchi against her own army (including the man who tricked her into unleashing the plague) in episode 12.
- Bokukko: She uses the male pronoun boku to refer to herself.
- Broken Bird: Machines don't betray you. Unlike Colonel Hopkins, they won't take advantage of a little girl to recreate biological weapons of mass destruction. Thanks to Kanata and Aisha, she gets better.
- Bunny-Ears Lawyer: She may not answer while driving, she may wonder at a pillbug, fall asleep at random, and be quite laconic, but she can repair anything, save those pesky Black Boxes.
- Child Prodigy: Singlehandedly repaired the facility used to manufacture a biological weapon known as the "Invisible Reaper" as a little girl.
- Defrosting Ice Queen: Filicia mentions that Noel has changed a lot since Kanata arrived. Noel also declares herself happy when Kanata doesn't arrive at the Clocktower Fortress on time, but by episode 4, she falls asleep on Kanata's shoulder.
- Failure Knight: Aisha reminds her of one of the victims of the Invisible Reaper.
- Heroic Albino: One of the main heroines, coming with white hair and pale skin.
- More Dakka: Her weapons of choice (other than Tank-Kun) are apparently always heavy machineguns with lots of ammo, be it a drum-fed MG42 or a bucket-fed water Gatling.
- Mystical White Hair: She's fifteen and white haired, and as seen in the flashback to the time she worked for Colonel Hopkins, she's been white haired since an early age.
- Not So Stoic: When faced with her Dark and Troubled Past.
- The Quiet One: Noel says very little and when she does have something to say, she uses as few words as possible to say it.
- Red Baron: Her connection to the Invisible Reaper bio-weapon earned her the epithet for herself, as well as the Witch of Helvetica epithet.
- Rei Ayanami Expy: White-haired, pale-skinned stoic pilot that hardly speaks, uses a monotone when she does, and has a Dark and Troubled Past coming back from when she was a Child Prodigy. She does have a Not So Stoic moment in episode 7.5, but otherwise fits.
- Sleepyhead: She has a tendency to pull all-nighters working on the tank, resulting in narcolepsy.
- Spell My Name with an "S": Noël.
- Sugar-and-Ice Personality: Deeply stoic and distant, but that's because she's severely emotionally scarred by her part in the Invisible Reaper. Underneath that cold exterior, there's a very kind-hearted and caring girl.
- Teen Genius: Repaired the super-advanced Takemikazuchi alone, in an old, dilapidated high-school gym and achieved fluency in
GermanHoly Roman in just under two months.
- Terse Talker: Noël is pretty concise when she talks. While she is sober.
- Unwitting Pawn: Hopkins used her to repair the facility that recreated the Invisible Reaper plague, giving her a serious case of My God, What Have I Done?.
- Wrench Wench: She's the Takemikazuchi Spider Tank pilot and mechanic.
- Zettai Ryouiki: Her nightwear.
Leader of the 1121st Platoon, Filicia adopts a very relaxed approach in commanding the platoon, beginning with her insistence of First-Name Basis amongst platoon members. She cares a lot about her subordinates and wanted them to be as happy as possible during their time in the Clocktower Fortress.
- The Anti-Nihilist: In episode seven, she declares life to lack meaning but for the one people give it themselves, and the meaning of her life is to protect her squad mates/surrogate family.
- Beware the Nice Ones: She doesn't hesitate for a moment to put a gun to the head of Colonel Hopkins, and later shut him up with a warning shot, in episode 12.
- Call-Back: During the battle of Vingt-et-un, shortly before Filicia's entire tank platoon was killed, Lieutenant Olga gets the tank moving with 'Alright, let's go, my girls!' During the Let's Get Dangerous scene in episode 12, Filicia says the same thing to the girls of the 1121st.
- Captain Smooth and Sergeant Rough: She's Captain Smooth, nicely suggesting "fun" things to do.
- Fear of Thunder: Filicia usually smiling, calm composure breaks down during thunderstorms, as seen in episode two.
- Flashback Nightmare: Episode seven has her flashing back to the time she spent trapped with a mummified soldier in a subway tunnel, triggered by seeing her own blood.
- Hair of Gold, Heart of Gold: Beautiful, young, humble, nice all around, and channeling all her guilt and sorrow into positive things.
- Hidden Depths: Filicia starts as the Team Mom, and grows into an Iron Woobie as we learn more of her past and motivations.
- Mama Bear: Filicia is a really nice girl... but make her girls cry and you'll regret it, as Hopkins learns.
- Meaningful Echo: See Call-Back.
- Meganekko: Pretty, always smiling and composed, giving orders that sound like suggestions, and a tad vulnerable.
- A Mother to Her Men: Filicia lists among the rules of the fortress that no one is to be addressed by rank, and she does every kind of menial tasks not usually performed by officers, like cleaning up the bathroom in episode 2.
- Phenotype Stereotype: Germanic name = Golden hair and blue eyes.
- Scary Shiny Glasses: Her glasses hide her eyes for serious effect in episode seven and for laughs in the first OVA.
- Shell-Shocked Veteran: In episode seven, it is revealed that Filicia is the lone survivor of her previous unit, and got chronic hallucinations and survivor guilt out of her ordeal. Doting on her unit is her way of coping with it.
- Stepford Smiler: She keeps all her serious psychological issues to herself.
- Survivor Guilt: Her crew was killed during Vingt-et-une, and she started having hallucinations urging her to join them.
- Team Mom: You won't find officers who give group hugs often.
- Unsuspectingly Soused: Can't really be called "unsuspectingly", since she knew she was drinking alcohol; more like soused after spiking everyone's tea and overestimating her own tolerance.
A miko/nun/priestess who works at the church and takes care of the orphans.
- Faux Fluency: Whereas Nami Miyahara's Aisha is pretty fluent in German - err Roman, Misato Fukuen clearly isn't. Fortunately Sister Yumina isn't supposed to be, being Helvetian, which means Roman is likely her second language.
- Nuns Are Mikos: An inversion of the usual example; she looks more like a miko, but acts more like a nun.
- Parental Substitute: She runs the local orphanage with a gentle hand.
- Rummage Sale Reject: Not so much herself - her hakama-habit is actually quite fetching - but she doesn't spare the children or Kanata her poorly-coordinated choices of clothing.
- Unsuspectingly Soused: In 'The Fortress At War', when Filicia spikes everyone's tea and gets them to drink several cups each. Less unsuspectingly later in the same episode, though.
An orphaned girl under Yumina's care. She is very protective of who braids her hair, since her mother used to do it for her.
- Berserk Button: Anyone but Yumina trying to braid her hair, since her now-dead mother used to braid it.
An orphaned boy under Yumina's care. He is hostile towards soldiers, whom he blames for his parents' deaths, although his view of the soldiers at the Clocktower Fortress improve with the passing of time.
- Heartwarming Orphan: Initially subverted, as he behaves in a hostile manner towards the 1121st Platoon, but warms up to them eventually, double subverting it.
- Suspiciously Specific Denial: His description of Kanata reads as follows: "She's easily amused, she forgets everything, she's just like a little kid, and she's not sexy at all!"
A courier and part-time standard bearer responsible for supplying the 1121st with their mail and their new recruits. Has the same name, and looks like, "Miracle Klaus", the Desert Wolf.
- Call to Agriculture: His Plan, after finishing his military service, is to become a farmer.
- Drives Like Crazy: He's good at what he does, but Kanata likely won't be riding with him again anytime soon.
A Roman soldier introduced in Episode 11 after she is found by Kanata and Kureha while on patrol.
- Bilingual Dialogue: Given that she only speaks
GermanRoman, much of her dialogue, including a major CMoH, requires a translation team fluent in German as well as Japanese.
- Breast Attack: Noel gropes her breast to forestall being stabbed in the neck with a syringe. It works very well.
- But Not Too Foreign: Her grandmother was Helvetian.
- Can't Get Away with Nuthin': She breaks a leg, almost freezes to death, gets groped, gets hunted as an excuse to ruin the peace talks and then shot, all just for crossing the frontier to try getting a peek of her grandmother's town of origin.
- Forgiveness: Aisha forgives Noël for her role in the Invisible Reaper plague in episode 12.Du hast genug gelitten, deshalb vergebe ich dir, auch wenn dir sonst niemand vergeben sollte. (You have suffered enough, therefore I forgive you, even when probably no one else will.)
- Viewers Are Geniuses: See Bilingual Bonus. The Roman dialogue wasn't translated for the viewers in the original airing.
- Walking Spoiler: She is the first contact the characters have with Rome, the enemy nation, and introduces the plot of trying to make peace between both nations. She is also the crux of Hopkins plot to spark war between them, by killing her.
War heroine and daughter of the Archduke of Helvetia, she crossed the paths of several of the girls of the 1121st Tank Platoon before they were assigned to the Time Keeping Fortress.
- Hair of Gold, Heart of Gold: Wholesome heroine, savior of lost people and perfomer of Amazing Freaking Grace.
- Hime Cut: Fitting her Princess status, this traditional Japanese hairstyle looks strange on a blonde. Her half-sister sports the same haircut.
- Onee-sama: Her half-sister pretty much worshiped her.
- The Paragon: Everyone who ever met her was inspired by her wholesomeness (in different ways), especially Kanata, Rio and Filicia.
- Phenotype Stereotype: Golden hair and green eyes.
- Posthumous Character: She only appears in flashbacks.
- Royals Who Actually Do Something: She was a revered Helvetian war heroine.
- Too Good for This Sinful Earth: Besides all her wartime heroism, she died saving a kid from drowning.
Owner of the glasswork shop and ally of the Clocktower Fortress girls.
- Apron Matron: She's in her forties.
- Friend in the Black Market: She acts as a go-between for smuggling illegal calvados as a side to her curio shop.
- Insistent Terminology: Does not like people addressing her in terms that would reveal her age and insists them on using the age-neutral "Naomi-san" instead.
A feared Colonel of the Helvetian army, also known as the Demon of Vingt. He serves as the eventual main antagonist, despite nominally being on the same side as the heroines. His desire is to provoke war from the Roman Empire. He plans to do this by kidnapping and executing the Roman soldier Aisha.
- Big Bad: He is the one trying to restart the war, while the heroines want to keep the peace.
- Blood Knight: He loves warfare and violence, and will restart the war just for a chance to fight some more.
- Colonel Kilgore: He actively wants a war between the two nations, purely because he loves violence and thinks society benefits from war.
- General Ripper: He is obsessed with defeating Rome, and will stoop to bio-warfare and ruining peace talks for this end.
- Hate Sink: While most of the characters are shown to be good people, he is a murderous warmonger who, in the backstory, manipulated the Witch of Helvetica/Noel into leveling three cities and killing hundreds, then tries in the present day to engineer war between the two nations by executing a Roman soldier and blaming it on Helvetica, and finally takes citizen hostage upon hearing of the ceasefire.
- Red Baron: The Demon of Vingt. Fits with his vicious, warmongering personality.
- To Be Lawful or Good: He is the lawful one, following his orders to capture enemy soldier Aisha, even though he wants to go beyond that and kill Aisha to spark war.
- Uncertain Doom: He seems to have died in an avalanche in the Final Battle, but it is not confirmed.
- War Is Glorious: His belief and justification for attempting to being back war between Rome and Helvetica is that war advances human civilization.