Triangle (FUUKI Mame)
I know that I lot of people hated Rio, and I understand where they're coming from. But I can't say that I don't understand her feelings, I think many people would have done something similar to what she did. On top of that she never really "inserted" herself strongly between Gaku and Masamichi. She confessed to Gaku (despite knowing that Masamichi liked him, which I admit is slightly unfair) but she was the one who ended the relationship with Gaku, and on top of that she made sure that Gaku and Masamichi got together in the end. I'm sure that Rio stayed with the two feeling immense guilt. The actions Rio took were out of simply and jealousy, and we're all human. In the end she apologized for her actions and I think she truly wanted them to be happy together.
Juliet no Baka