Heo Jeong-woo, a high school student who is bullied by a girl in his class for his weakness. Han Bo-ra, a transfer student, comes to Jeong-woo's class, where he was spending his miserable days. Jeongwoo feels a strong sense of déjà vu when he sees the child with straight black hair and stains on his legs. Sure enough, Han Bo-ra, who has subdued the arguing classmates, asks them. 'Have you ever seen a child similar to me?' Jung-woo decides to approach Bora, who might be able to correct what is wrong...