Gong Joon Soo (young) goes to pick up his father, who gets released from jail. There he meets a woman, who his father introduces as Joon Soo's new mother, Jin Sun Hye. He is then introduced to his stepsister, Kim Jin Joo, and stepbrother, Kim Hyeon Seok, who shows their dislike to the 2 new family members. Joon Soo and hisfather let themselves being called as 'Oi' and 'Hey'. Joon Soo went back to school. Though he is 13 years old, he is a 4th grader and is placed in the same class as Jin Joo. Their brother-sister relationship is soon known by the school, so Joon Soo begs to change classrooms. The different surnames whithin the family brings discomfort for Jin Joo and Hyeon Seok.