Teenage Swordsman is a Manga/Manhwa/Manhua in english language, Action 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

From the creators of [Mercenary Enrollment/Teenage Mercenary]…

The story takes place in the world-famous online VR game, ‘Quest Hero’. A famed player of Quest Hero, ‘Harang’ ends up being taken to another world by a mysterious black entity. No matter how much he tries, he can’t log out, and he’s even attacked. Not only can he feel pain, he meets the real ‘Yuta’ and not the NPC Yuta. Can Harang complete the ‘7 Quests’ and return home safely? Thus begins the tale of the ‘Teenage Swordsman’ Harang, who fell into an unfamiliar world!