[Maekawa Hayato] Onee-chan ga Doppelganger ni Netorarechau! ch.1-4 [desudesu]

A boy named Shouma comes face to face with a copy of himself standing in his bedroom, and quickly learns the doppelganger shares every sensation he feels, a link it ruthlessly exploits to seduce his busty older sister Ryouka under the same roof. Helplessly connected, he experiences his sister's moans and climaxes secondhand while spying on the pair, jealousy and guilty heat twisting together as she mistakes the imposter for him. When even more doubles pile into the house and the sisters end up tangled among them, Shouma has to man up and fight to reclaim what's his, ending with both girls drenched, devoted, and begging him for more.