Amagami SS: Tachibana Miya-hen – Imouto S01

Mia Tachibana thinks her annoying little brother Junichi is going to be unlucky in love and end up alone, so she decides to spy on him out of curiosity at school. She's heard that some of his friends think Junichi is a kind and caring person. When Mia starts spying, she notices that Junichi is really nice to the girls at school, which leads to a bigger misunderstanding; because Mia mistakenly thinks that since Junichi doesn't have a girlfriend, he must be interested in guys.