Valkyrie Drive: Mermaid

VALKYRIE DRIVE: Mermaid (マーメイド Māmeido?), a television anime series produced by Arms Corporation, which aired in Japan between October and December 2015, the anime portion of the Valkyrie Drive franchise.

The story begins on Mermaid, one of five islands in the series where those infected with the Arms Virus are sent, segregated from humanity to contain the infection and limit the danger of the virus. The protagonist Mamori is sent there, utterly ignorant of herself having the virus, and nearly gets killed not long after showing up by two lesbians, one of which tries to kill Mamori with the other turned into a gun used by the other lesbian, only to be saved by another girl named Mirei, another recent transfer who thankfully knows a little more about the situation, activates Mamori's latent powers to turn Mamori into a sword, and saves them both.

Tropes used in Valkyrie Drive: Mermaid include:

Artistic Licence Biology: The Arms Virus clearly could not feasibly work in any way in reality.
Artistic Licence Law: The way the United Nations is described does not at all match how it works in the real world, as the in universe version seems to have one world government level authority, though since the party that mentions this is mostly speculating, this may or may not be the case.
Blessed With Suck: The Arms Virus instantly makes you a social outcast who is sent to one of five islands in most cases where you have to live apart from society, with the debatable hope of ever being able to go back to the rest of the world. The other alternative is be liberated from there by a shady organization who is almost certainly not liberating people with their best intentions in mind. And while the island is surprisingly comfortable and civilized, getting killed is an almost constant threat due to how fight happy practically half the population is on any given day.
- Cursed with Awesome: On the other hand, the disease has no other real drawbacks to those who have it, and if you're a lesbian and like to fight, exile to the islands is essentially a Warrior Heaven on Earth.
Beneficial Disease: Technically speaking, the Arms Virus isn't a problem for those afflicted, granting Liberators enhanced abilities and Exsters can turn into weapons the former can use to defend them both.
Ecchi: The only reason whatsoever this isn't outright Hentai is because nothing between any female characters legs is shown, and the show is full of, at bare minimum, softcore lesbian porno.
Equippable Ally: How the Arms Virus functions for half the afflicted, called Exsters, who turn into weapons that the other half of the afflicted, called Liberators, can use.
Fundamentally Female Cast
Girls Love: It's a series about a virus that affects only women, sent to an island with only women save one possible exception nope, it's just a very Bifauxnen woman, and the virus gives them powers that revolves about sexual arousal which they need to use to survive, and requires they partner up with other infectees to make use of those powers.
Plot With Porn: To Seikon No Qwaser levels. There is an actual plot, but even that is loaded with Cinemax level late night movie lesbian scenes in anime format.
There Are No Therapists: Everyone exiled to the islands was usually in their teens, there is little to no adults except those that grew up there since their exile, there are no medical staff despite the fact everyone on the islands is quarantined there due to a virus, and there is no psychiatric help available for anyone involved.
Unfortunate Implications: Women can be infected with a virus that turns them into a weapon that can become symptomatic as young as nine years old, and some of them have used as child soldiers. The easiest way to trigger their abilities is based on sexual arousal, and thus the implications don't need further explanation.