One day, my father suddenly says to me, "I think you'll need a new mother, Keita." My real mother passed away when I was a kid. I was sad at first, but I somehow managed to accept it. But why now...? Anyway, my father brings four ladies in front of me and says, "The girl who goes with you the best will become your mother. You live with them for a while and grade them." I don't need a mother anymore, so I just give them all low grades. Like this, I start living together with four ladies...