In which you -the lucky one who managed to score that ever elusive first kiss from the boy you like- realize that you aren't the only one who's fallen for him. Of course, he's a bit to dense to really get the message, so given his obliviousness, it's up to you to arrange things so that everyone's happy.
...and if that means you get a bunch of cute girlfriends too, then that's a trial you're willing to endure.
You are the best friend of a harem protagonist , your job is to protect him and his other friends and stuff. Maybe even be his boyfriend(that's your dream).