Keita has two older step-sisters, Ako and Riko, but since they aren't related by blood, they love him in a lustful way. After a mishap at school, Ako and Riko finally confess their love to him. Keita dislikes the thought of seeing them other then brother and sister, but as he tries to enter the same school as his sisters, he slowly becomes attracted to them.
The story, of course is "different" and weird. But the whole thing is funny, and it pleases me if watching it.
I love the animation, and i love it more, when i see those sisters or Keita beiing embaresed!
This anime, is watchable but surely doesnt has the "action" and the "agony" of other animes.