Mr. Security, Please Sign for Your Princess

I Am Asking for an Article. the Male Protagonist Took the Elixir and His Hair Turned Gray. He Had a Period of Weakness for a Few Days Every Month.

The male protagonist is a waiter in the palace. He and a group of people went up the mountain to ask for the elixir. They found two elixirs. Only people with the right constitution can live forever after taking the elixir. After taking the elixir, the hair turns white every once in a while.