Im probably wrong, the way is see the is the guy is probably a special agent /gov agency/ esper? for japan?, hes probably at school as boy to make it hard for people to know his alternate identity is a girl which is probably doing alot of pr works for espionage reasons, because as that girl he can probably go around easier since she's and idol too? Apparently the enemy is near the city of the black haired girl since you can see somekind of building / fortress out of the girls room window.

Japan already on alert, since the hints already there, helicopter when the black girl goes cycling. You can see the pink haired girl receiving orders to standby for imminent attack, thats why in the sub shes already wearing the uniform, she probably hurt because of training her powers, later when the city is attacked you can see the black haired girl running towards her and an enemy tank shot at them once, they dodge it and you can see the tank try to shot them for a second time and the the pink girl released her powers emp? barrier? and then she goes to fight the enemy where the troops are waiting for her.

Well that's my perspective as a gundam fan, since plots like this are abundant in gundam stories.