Intertwined (Sicong)

 A famous demon slayer during his lifetime died and is now a demon in hell. Still persuaded with the urge to kill every demon there is he wants to slay them all. With the goal of ending the suffering of earth by defeating Satan. Firstly, he needs to become stronger to overpower any enemies he might find. While adventuring trough the deepest of hell you might find hidden treasures and demons you never wish to meet.  

The story has two ending, if he killed the hidden boss Satan, he would become the new demon lord. If he only killed the 5 main bosses, he will be able to escape from hell, but he'll be hunted by the demons forever.