Neechan no Tomodachi ga Uzai Hanashi  

My Older Sister's Friend is Annoying, 姉ちゃんの友達がうざい話

Nao becomes agitated with Sena, a boisterous friend of Rio's sister, who is excessively meddling. However, what annoys him most is that she cannot recognize him as anything other than a child. Is there any way for him to help her understand?