Sono Hanabira ni Kuchizuke o - A Kiss for the Petals

The first installment of the series, this particular game follows Nanami Oda, who is a new freshman in high school. However on the first day, she ends up in an accident in which a senior student from the school comes to her rescue. Ever since that meeting with Yuna Matsubara, Nanami just cannot get her mind off of her and later decides to join the student council. But one day...Nanami catches Yuna doing something very strange-(masturbating), while also calling out Nanami's name.