Boushoku-Hi no Ken 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.nl fastest updating comic site. The Summary is

After Dean, a third rate adventurer, got surrounded by demonic beasts in the demonic labyrinth, he fled to a place where he found the strongest demon who devours power: The demon-fed sword Belzera, born to the Gluttony Empress Belzebuth. After obtaining such unexpected power, he once again aims to become a first rate adventurer he looked up to, and delves deeper into the labyrinth. However…