Kurashihara Izumi (played by Ai Iinuma) is a student who has always maintained the first grade in his sophomore year. One day, there was a rumor in the class about an incredibly handsome transfer student. However, the rumored mysterious transfer student has been absent since the first day, leaving only one name on the blackboard: "Grandfather Jiang Guangshu". The students began to speculate about his identity, some thought he was an idol, and the girls were immersed in fantasies about their grandfather, E. One day, the head teacher entrusted Izumi to deliver his homework to his grandfather Jiang's home. Walking into her grandfather Jiang's house, she was suddenly asked by his mother to become her son's friend. So, Izumi learned about his grandfather Jiang's LINE account and began to communicate with him secretly, all of which was hidden from his classmates. Izumi gradually discovers that his grandfather Jiang is not the perfect image that everyone imagined. He may be an otaku and not interested in socializing. However, in the company of Izumi, his grandfather Jiang gradually opened up and shared his interests and feelings. Their communication has deepened, and it is no longer limited to homework and studies, but has become a sincere friendship.