Plaything is a Manga/Manhwa/Manhua in english language, Drama series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Lee Myung-jun, the Vice Chairman of Hyundo Group, lost his daughter to a group of bullies. Seeking revenge, he adopts Yoon Karma, a psychopathic defector girl.

Yoon Karma: A sadistic human weapon created through drug experiments in North Korea. After killing everyone in the research lab, she escaped to South Korea on her own.

Having just been released from a juvenile detention center in South Korea, Yoon Karma sets out to hunt down the bullies at school, driven by the desire to avenge her new father and satisfy her sadistic pleasures.