Kyou Mo, Karera No Otonari De summary:

When a new family moves in next door, Nao is curious to meet them. After watching them move in, she discovers that the family has two sons: Kyousuke, a handsome and playful boy who’s the same age as Nao, and Tomoyasu, the younger brother with a scary face and unapproachable personality. At school, Nao finds that associating herself with the attractive brothers could put her in a difficult position, so she pleads to Kyousuke to keep their situation a secret. How will Kyousuke react? And how will Nao, a seventeen-year-old with no experience in love, deal with his response?!