Konomi ja Nai kedo: Mukatsuku Ane to Aishou Batsugun Ecchi 1

Ritsuki Miyama and her older brother Kyoya fight every time they see each other. They're so bad that they start fights even in front of their friends. One day, Ritsuki comes home in a hurry in the rain and bumps into Kyoya at the entrance. Ritsuki gets angry, but she freezes when she sees Kyoya's bare, wet upper body. His body is exactly the muscular type that Ritsuki likes. Ritsuki realizes that Kyoya has noticed her staring and tries to leave quickly, but she bumps into Kyoya again and sprains her ankle. Kyoya enters Ritsuki's room with a compress and bandage, and he becomes conscious of the fact that he is of the opposite sex in his sister's room, which he has not entered in several years. Kyoya tries to shake off this awareness and leave the room before things get complicated, but Ritsuki asks him to give her a massage. Kyoya reluctantly agrees to her request because he feels guilty for causing her injury, and while he is massaging her, he realizes that he likes his sister's body.