Jigokuraku 2nd Season

Gabimaru, a deadly ninja known as the Hollow, was sentenced to death. But all the attempts to kill him failed, and he believes that he deserves to die. Sagiri Yamada Asaemon, a young executioner assigned the mission to kill him. Instead of killing, he gives him another chance because of his love for his wife. Sagiri gives him the task of travelling to the island of Shinsekyo and bringing back the Elixir of Life. If he can do this, then he will be free to live happily with his wife. Gabimaru accepted the mission, but that island is full of deadly things.