My Diary ～君が僕の妹だったら…～

Momo, Rika and Nozomi are friends with each other and they have common affection for Tsuyoshi. However, Tsuyoshi gets in a traffic accident and with time girls' attention shift to main character. Protagonist is actually the older brother of Momo. Even though she understands her feelings can't be fulfilled, she can not tolerate that her brother was in love with other girl.