Iron Mountains Eternal Coffin

The Demon King Masaru Nanahoshi has died. Those were the words the world heard after they had expected to go to war for well over 1000 years.  The demon king had sealed himself under the Iron Mountain because he was bored with the world. But before he did that, he had left the world with a warning: if they were weak after 5000 years, he would annihilate them all. Well, Kit Arthur Alba knows that is far from what the demon king had said.  This is because he is the reincarnation of Masaru Nanahoshi,  But he also knows he wasn't that great of a person in his previous life. Will he follow in the same footprints or choose a different path?