Nine Regrets Demon Lord

Once you become a demon and enter this point of no return, you will be condemned in your heart, confused about the way forward, and trampled on your soul, making you lonely, helpless, lonely, and painful than before. However, after the birth and existence of something one day, all the loneliness and pain will disappear, leaving only a faint complex feeling... Because, there is always "self" behind the scenes who silently endures everything. He is probably just a villain who likes to leave all the pain to "himself".