Angnyeogyosil

Heo Jeong-U, 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-U's class, where he was spending his miserable days. Jeong-U 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?" Jeong-U decides to approach Bo-Ra, who might be able to correct what is wrong...

(Source: Naver, translated)