Your name is Hope Suzuki, no connection with the brand. You were born in the U.S. like your parents, but both your maternal grand-parents and your paternal grand-father are from the Hokkaidō prefecture in Japan, which mean you might have some Ainu blood. Your father know what you truly are. Apparently, there was a succubus princess who fled hell and its doctrine on his mother's side, causing some of her female decedent to be born as succubi too, like you. Unlike your father, your mother don't know you are a demoness, but its not because you hide it from her, she is just too stubborn to accept the supernatural to be real… Or that she might have Ainu blood, also.
A few month after entering middle school it was attacked by… you can't remember well, that part of your memories is strangely blurry, but clearly mythological being. Then a group of warrior-angels came to help, but their leader gave a really bad order, which caused the death of lot of his men. At first, you tried to help your fellow students to evacuate, something the angels should have helped with, but that's another thing the orders from their incompetent chief prevented, trapping everyone there instead.
Feeling like you didn't have much choice, you decided to fight. Not so much for your survival than for everyone else. Of course that meant revealing your true self to all present, which scared a lot of peoples, but then they saw you fiercely fighting the… Whatever was invading the school, and they started cheering you, some even joined you.
Most of the peoples that were fighting at your side weren't human. Sure, there was all the angels, but also some of the students, trowing away their disguise, often a rather shady one. (Honestly, how didn't you see through them is a mystery to you.) Like that girl named… …Who was a… Or that boy, turning out to be… Why can't you remember? Some of those peoples became your best friends, for god's sake!
Anyway, in the heat of the moment you ended up barking orders to everyone, not realizing what you were doing. Strangely, outside of the warrior-angels' leader, everyone obeyed you. No complain, no nothing. And somehow, you drove back the invading forces. It didn't stop the incompetent one from berating you for butting into his operation, but both his subordinates and your fellow ‘monsters’ defended you, along with some of the teachers and other students. He would probably have killed you, if it wasn't for god's intervention.
Long story short, god sent two team of Valkyries, an elite cast of female angel-warriors, to help with clean up, along with their supreme commander, Freyja.
Normally, clean-up would have included erasing everyone's memories of those events, replacing them with fake ones, but Freyja had a propositions for all those that helped against the invasion. It was a known thing among angels that Valkyries accepted non-angels in their ranks from time to time, but she was really impressed by how, as a total novice, you were able to turn around the battle's outcome.
She gave you, on top of the education you were already receiving, all the lessons you would need in combat and strategies to be a good Valkyrie, before recruiting you as a team leader. Any other non-angel having participated in the fight could also join, but as ‘simple’ Valkyries privates. Only a few of your admissible schoolmates accepted the offer, and you still can't remember their face, name or species, to your great shame. The ones who refused ended up forgetting what really happened that day, like everyone else.
About your lessons as a future Valkyrie, it ended up with you going in a new school. Officially, it's a private school who goes from middle school to college, offering scholarship to any students its board find promising. (In what are they promising? They never say.) In truth, a place where god regroup all young people he find to be… of interest. (So it wasn't surprising that even the ones who refused Freyja's offer ended there too.) This school having an excellent reputation, few parents refuse said scholarship.
To your surprise, your Valkyries lessons didn't take all your schooling and, after only two years, your friends and you became reservists Valkyries, hence the silver flange on your armor rather than a gold one. Concretely, being reservists Valkyries meant your team was only sent on missions on your free time, and only if you all had finished your homework. …Unless there was very special circumstances.
Because of how they work, the Valkyries' hierarchy is a bit special. Each team leader answer directly to Freyja, who's official rank is Corps General, Freyja herself answering directly to god himself. Below a team leader, there is only privates, (or equivalent) but with far, far more ‘class’ than there is in any other armies. The higher the ‘class’ number, the higher the rank (and the pay). So while all other members of your teammates started as ‘simple’ privates, as team-leader you started as Brigadier, the Valkyries equivalent of a Corporal, and got all the way to Lieutenant. (A recent promotion, a week ago your rank was simply Sub-Lieutenant.)
Of course, a non-angel being nominated as leader of a team of Valkyries, even a reservist and mostly non-angelic one, was bound to displease some of the angels in their most classic military. Hence why your team have an ‘ice-phoenix’ instead of the classic, fiery one present on the chest of every other team of Valkyries, (your idea) so the so called ‘protectors of morality’ among the angel-warriors would think you weren't given the title of ‘true’ Valkyries. But Valkyries you are and as such, when on one of your missions you stumble into the operations of a troop of non Valkyries, if it's directed by someone of lower rank than you, you are to take over which, let be honest, became almost guaranteed since you became Adjutant-Chief. Otherwise both operations stay independent, and hope you won't undermine each other.
Still, all those holes in your memories worry you, which you share with the shopkeeper. "Hm… You must be part of a set, then."
"A set?"
"Yes, that's when this magical mall give intermingled pasts to at least two peoples. You'll have to wait for them to finish their own transformations before going out of the mall. I am right in assuming you're waiting after your squad members?" You nod firmly. "Then you'll have to spend time in the waiting room I have for just those kind of situations. But before, let me open the secret armory for you. After all, what kind of warrior don't have a weapon?"
He discretely guide you toward a secret room behind the counter, and you find yourself in a place full of all kind of blades, war-hammers, staffs and even some firearms. Again you let your body walk and take a weapon, just like you did with your armor and your underwear, and end up with a naginata. The fact you ended up with a weapon from Japan put a smile on your face. As you look at it, you notice its blade changing to become an exact replica of the one at the top of your tail. "Angelic weapons are special," the shopkeeper inform you "they are linked to their owner, almost like they are a part of them. Your naginata can't hurt you, and nobody can use it without your agreement."
At this you make your precious weapon disappear, knowing you will be able to retrieve it the second you need it, and follow the shop owner to the waiting room, sitting in an armchair.
Not liking to be in armor while out of duty, you used its propriety to turn it into something more appropriate for an everyday outing. It now look like black, form fitting pair of jeans on your legs, and an ice-blue camisole, no trace of your ice-phoenix or your rank among Valkyries left on you, almost looking like an ordinary high-schooler, which you mostly are when out of duty, to be honest.
Now, all you had left to do was wait for your team to arrive.