Jeongin is a kindergarten teacher loved by both children and their parents. But no job is perfect and there are many difficulties that one needs to face. And Jeongin thought he saw everything but a new boy that got into his class has become his new "difficulty". The young woman that was bringing and taking the boy, Kim Binna, had to come in one day for a meeting, revealing the boy's life story to the young teacher. Now, they both take on the mission to help the child become a happy and cheerful boy. But all that darkness his little self is holding starts to affect the teacher too. In the end, everyone needs help... A warm hug. TW for depression