Keita has two step-sisters who love him in a lustful way and have no problems expressing it; they are even competitive about their affection towards him. Much to his chagrin, as well as the amusement of his friends, he endures it.
However, when one day they come to his school to give him his lunch, he gets annoyed and explodes on them. They then confess their feelings for him in front of everyone and leave.
Feeling sorry for them, he chases after them and says that he'll study hard in order to get in the same high school as them.
Not only that, an otaku teacher with a lustful body, a loli kouhai and a busty classmate take interest in him and little by little become closer to him, causing many misunderstandings and complicated situations...
Will Keita be able to get into the same high school as his sisters? Hill he endure forever his sister's ero attacks? Will he succumb to any of the other girls' attacks?... Lots of ecchiness and fun is assured!