Onii-chan wa Watashi Dake no Mono nan Dakara!!

My name is Rino Onodera. I'm not really a good student or athlete or cook or anything, but my friend tels me I'm pretty. When I joined school I got 121 love letters. 99 of them begged me to date. I had to give 99 rejections. The thing is I don't care about other boys! I have one love in my life, and he's my big brother. Yusuke Onodera! But he never notices that I'm giving off love vibes. In fact, he got a girlfriend recently!! He even introduced me to her! Oniichan, get a clue! You're killing me here! Not only that, she's a really pretty girl and she can cook and she's nationally ranked in tennis and she's I dunno an alien or an angel or a demon or something, the point being she's superhumanly perfect!! And her family is rich! Isn't that kind of too unfair!? I can't let my brother go without a fight. Oniichan is mine! She may have all the advantages, but I won't lose! I'll do whatever it takes to take him back. [Simplified description from English DLsite.]