A demon king suddenly stepped down from his throne because of an unknown reason which lead anyone to curious about it. Then a bounty hunter, who wanted to kill the ex-demon king, appeared and stole the secret potion. Believing that it will make him powerful, he drunk it and then their story begins to unfold. What's the use of that potion and why it's a special secret? Will this bounty hunter, who is a runaway princess, help the ex-demon king keep his secret or she will be the one to reveal it?