Since she was young, Karen has dreamed of becoming a teacher. She put all her effort into it and finally realized her dream. After a week of internship at a new school, she was assigned to be the homeroom teacher of a class. She tried to memorize the students' names and called them by nicknames. Karen was well-liked by the students except for Hayato. He often skipped class and got into fights with students from other schools. Karen wanted to help him and wanted him to open up to her. She frequently met and talked with Hayato, shared a diary with him. Gradually, feelings developed between them. Even though she knew this was not allowed and could shatter her childhood dream, she loved Hayato! They ran away together for dates, went to hot springs, enjoying moments of a couple in love... "I love you," "After you graduate, let's get married, okay?"... A beautiful but forbidden love, they were separated but their hearts would always be together...