3x3 Eyes, Ajin Recommendations
The main protagonist in both manga find out that they are immortal and can regenerate after they die. Both manga deal with the idea of what it means to be immortal and that the main protagonist in both manga have to use their newly found power to fight against evil forces. Both manga are also both filled with violence, action and blood with a dark and gritty atmosphere. If you liked one, you'd like the other.