Based on the adult maga by Yuzuki N'.

Honoka arrived at home with snacks, juice, and candies which are her brothers, named Hirokazu, favorite stuff. However, she noticed there has been an unexpected guest - Akasaki. She attends the same class as Hirokazu and for that matter he invited her for a study session and Honoka misunderstood her as his girlfriend. Will Hirokazu make up with his sister in a secret way while Akasaki is still in their house?