BLACK CORPORATION: JOSEON 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

The maniac who was crazy about all kinds of fields such as military and steampunk had been reincarnated. However, his father was King Sejong the Great? The mania-wise king and his crazy maniac son. Along with the ministers, and countless humans who were getting exploited. Even today, the night of Joseon was filled with the light of overtime.