I BECAME A TERMINALLY-ILL KNIGHT 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

Levis Cloyd, a man who transmigrated from Earth to another world, is bound to live a time-limited life. To survive, he must kill living beings. Living with the motto of "if you are going through hell, keep going, " he meets another opportunity.