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

Was that a giant face that floated past the window in the back of the class? How does some self absorbed guy always get a perfect score on the exams? In this world people wield items called ‘Bai Wu’ and they all have powers! Danger is around every corner, as enemies shrouded by shadows, lay in waiting! For the sake of survival we fight!