Osana and Senpai have been close friends ever since they were very young children. They have always lived next-door to each other, and have always walked to school together. Despite their closeness, Osana is quite rude and harsh towards Senpai; she is always easily irritated and quick to anger when he is around.

"You baka! You left me waiting again, you dumbass!" She spoke bluntly at her friend, Taro Yamada.