Radiance of Tribulation: The Old Man Leads the Way is a Manga/Manhwa/Manhua in english language, Manhua 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

Together with the Demon Lord, he is reborn 60 years into the past. Witness how the dashing elder mercilessly crushes the Demon Lord, all while safeguarding his beloved.