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. 
(Source: Anime News Network) 
 
Note: The first episode was aired as an online preview on Bandai Channel between 25th and 26th of March 2010. The regular broadcast started on April 5.

Keita is studying hard for a high school entrance test, but his two beautiful elder twin stepsisters are a constant distraction. Though they mean well, Ako and Riko are also extremely sexually assertive and interested in Keita. At first, he fends them off, but little by little, with each kiss, Keita becomes close to both twins until a forbidden love triangle develops. Will taboo-breaking love bloom between two of them... or will Keita at least get into high school?! 
(Source: Discotek Media)

Keita has two step-sisters who love him in a lustful way and have no problems expressing it, they even are in competition about that. Much to the laughs of his friends, he endures it but when one day they come to his school to give him his lunch, he gets annoyed and explodes on them, then they confess their feelings for him in front of everyone and leave. Feeling sorry he chases after them and says that he'll study hard in order to get in the same high school as them. 
(Source: MangaHelpers)

Suminoe no Haha