The owner of Minamikaze has invited the girls of Lemon to his home, once there the mood changes drastically.  How can the girls escape?  Squid Girl is suffering from amnesia and everybody is trying to convince her she is an alien, girlfriend, or sister, but what about invader?  The Invasion Club has been formed, join and watch how they systematically invade the city.
By "invading," you just mean 
going out and having fun!
Mit "Erobern" meinst du "Losziehen und Spaß haben".
Dicen que están invadiendo,
 pero en realidad solo salen a divertirse.
Decís que estáis invadiendo,
 pero en realidad solo salís a divertiros.
Vous dites envahir pour la forme,
mais vous ne faites que vous amuser.
Quando dizem "invadir", só querem 
dizer que vão se divertir!