Sang is the primary antagonist of the RPG game, Seven Mysteries.
About a year ago, before the game began, Sang took part on in a young girl's murder along with other students. One student, Linh, tried to leave the school, but Sang murdered him along with other students involved with the girl's murder. Once the headmaster heard about Sang's crimes, he decided to allow Sang to continue killing instead of turning him into the police.
He initially starts as an innocent bystander who tells a tale about the cursed school. In one of the other students' tale , he is also a victim of a nightmarish hallucination, watching one of his friends dying. However, once Tuan discovers Linh's notebook, he is revealed to be a sadistic psychopath and is determined to kill Tuan.