Keppeki joou no Yarikaeshi is a Manga/Manhwa/Manhua in english language, R-18 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

Ellen, the exiled queen of the country, visits a famous blacksmith in search of equipment that will allow her to fight a black dragon who destroyed her palace and kingdom. The blacksmith is not convinced and things begin to turn interesting... as he demands his rewards upfront!