Neechan no Tomodachi ga Uzai Hanashi Neechan no Tomodachi ga Uzai Hanashi

Nao grows frustrated with Sena, a loudmouthed friend of his sister Rio, who is too nosy for her own good. But what irritates him more than the constant pestering is how she just can't see him as more than a little kid. Can he help her get a clue? (Source: Irodori Comics, edited)