In the year 2088, humanity is at war with a alien force whose firepower greatly exceeds their own. Humanity had been pushed into a corner with only some of the biggest cities still standing. If things go on like this then there's no telling if we will survive.
However there is a small hope that we can grasp.
At the start of the invasion, the US government found ten weaponized suits hidden underneath a farmhouse after receiving an anonymous tip-off. A single one of these suits contain enough firepower of a small army and can adapt to any circumstances.
However there is a catch.
The suits can only be worn by men, but when a man wears it they will find their body turned female. They will return to their normal body to days after they take off the suit, but if they put on the suit again then they'll be turned female. The suit also transforms the body a different way each time. It is theorized that the suits are purposely transforming the user in order to maximize combat potential. So while one mission will have the user be a normal caucasian woman the next mission might see him transformed into a Japanese woman about 19 years of age. Notably most transformations have resulted in women over the age of 18, but their have been some exceptions. Their have also been some cases of users turning into female mythological creatures such as a gorgon or females with animal traits such as catgirls.
Due to the constant shifting of their bodies, users will be designated and called by the number of the suit given to them at all times. (00-09).
Another problem with the suits is how they obtain their power. The suits receive their power from sex. A single night of sex can make the suit last four missions at least or 6 missions max. However, to properly power the suit the user must be wearing the suit. Meaning the user will have to have sex as a female. Their partner can be female or male, but it seems like if their partner is a Male then more power is received. To this end, user must go to one of the remaining cities after every three or four missions and have sex with a partner returning before two days.
The suit does not stop pregnancies. If a user is pregnant while they are refueling, then instead of becoming male again after two days they will remain female. The suit seems to actively encourage pregnancies, as when the suit is worn the pregnancy increases in speed. It was also discovered that the suit will no longer change its user if they are pregnant, preferring to keep them in the form they got pregnant in, and the power of the suit will increase exponentially to protect its user.
The UN has created a private military branch in order to utilize these suits, which are now being called the Succubi Suits or SS for short. The goal of the organization is to finally repel the unknown alien invaders, designated "Angels." Governments all over the world are testing compatibility within their military and even their civilians are being tested.
A new person has entered their ranks chosen to wield the suits to save mankind.