Since she was a child, Karen dreamed of becoming a teacher. She put in all her effort and finally achieved 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 learn the names of the students, calling them by nicknames. Karen was well-liked by the students, except for Hayato. He often skipped class and fought 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 the two. Although she knew this was not allowed and could shatter Karen's childhood dream, she loved Hayato! They ran away together for a date, went to hot springs, and enjoyed moments as a couple... "I love you," "After you graduate, let's get married, okay?"... A beautiful but forbidden love, two people separated but their hearts will always be together...