Karin, who is fair-skinned, cute, and popular at school, is a kind sister who adores me and always looks out for me, her unattractive older brother. One day, she says, "I have something to show you," and shows up at the school festival dressed in a risqué maid outfit! However, when I tell her that I can't go to the festival because I recently got a "girlfriend," Karin gets jealous and forcefully and boldly tells me, "I know you better than you do, big brother..."