Area 88 can be a bit brutal. We have a pilot fighting to survive in a war that he never wanted, because his friend set him up to remove him from the competition for the top seat in an airline.
Full Metal Panic! has a private military counterterrorism organization called
Mithril. One of their men, Sousuke Sagara, a child soldier who was later recruited into the organization, get assigned to be a bodyguard as it allows him to "blend in" as he's the right age. But that doesn't work so well. It's part romantic comedy with mecha combat. At least three series.
Blue Drop - five years before the start of this anime, an alien spaceship tested a weapon they believed would pacify the humans living on a small island - instead, it drove both the ship's crew and the island inhabitants crazy, killing each other. On the island, only one small girl was found alive by rescuers, Mari Wakatake. Now a high school student, she is transferring to a girl's boarding school - and her room mate/class rep is the captain of the alien scout ship. One season, may be hard to find.
Iriya no Sora, UFO no Natsu (Iriya's Skies, Summer of UFO's) - The war started in 1947, it's just that nobody's noticed. Iriya Kana is the last surviving pilot fighting a secret war against aliens using a very advanced aircraft code-named Black Mamba. She's also a teenage girl - and she just met a boy, Naoyuki Asaba, both sneeking into the school pool for a private swim before the start of classes. Six episodes, may be hard to find.
Episode spoiler
In one of the final scenes, you see her fight suit with chest armor - and it's covered in prayers and well-wishes, like the Kamikazi before they flew off to battle.
And two more -
Arpeggio of Blue Steel alien AI warships that look like WW2 battleships but with highly advanced alien weapon systems have crushed the navies of the world, but one of the alien submarines, I-401 (Iona) was found adrift in a harbor following a battle. It was hidden away in a drydock bay but defeating all efforts to gain entry. It turned out she was just patiently waiting for the right person to come along. Mostly a rogue unit taking on alien forces directed by Mental Models that are all female (ships have female names, right?). Mostly ship battles, some fan service. Incredible art.
Tactical Roar - a super hurricane known as the "Grand Roar" has been raging for half a century in the Pacific, affecting not only the climate, but the flow of sea traffic and a rise in piracy and terrorism. To combat this, private military corporations offer escort services to merchant vessels. One of these is the
Pascal Magi, an often discounted ship as its crew is complete female. Some comedy, fan service, and ship combat. This may be hard to find.