Elixir of Immortality

The Elixir of Immortality (不死のエリクサー, Fushi no erikusā) is the one behind everything that happened in the history of Zombie Land Saga, a curse will fall on those who seek from it the source of eternal life.

Actual legend
The ruler of Qin, Qin Shi Huang, feared death and searched for a way to live forever. He entrusted Xu Fu with the task of finding the secret of immortality. In 219 a.C., Xu Fu was sent with three thousand virgin boys and girls to retrieve the elixir of life from the immortals, including Anqi Sheng, who supposedly lived on Penglai Mountain in the East Sea. Xu Fu sailed for several years without finding the mountain. In the year 210 a. C., when asked by Qin Shi Huang, Xu Fu claimed that there was a giant sea creature blocking his way, and asked the archers to kill the creature. Qin Shi Huang agreed, and sent archers to kill the giant fish. Xu then set sail again, but never returned from this trip. The Documents of the Great Historian say that he came to a place with “plains and wide swamps” and proclaimed himself king, to never return.

According to the tradition of Saga City, Saga Prefecture, Xu Fu came to the Ariake Sea, where he decided to float a cup on the water and go ashore where he made landfall. As such, the place where he landed the cup is known as “Bubai”, which literally means “floating cup”.

Xu Fu reached the top of Mount Kinryu, where he met a hermit and obtained the elixir of immortal life. The name of this elixir is Furofuki, and it still grows on Mount Kinryu today.

Anime and manga
It is mentioned in chapter 5 of Gaiden as the origin of Saga's curse. The actual background, in the legend of Jofuku, gives a lot of important information.

Uses
The main speculated use is to make someone “immortal”. It should be noted that if the Jofuku elixir is given by Anqi Sheng, the “immortal” Taoist for the Taoist understanding are not exactly “immortal” as in the Western understanding of “eternal” or “unaged” forever; instead, they would just live an incredibly long life and eventually die of old age at some point.

Jofuku's immortality properties seem to go this way a bit; he will live as long as Saga continues to exist. As he says: «I am Saga. No, Saga is me» It is strongly implied that his life and his immortality properties are tied to Saga herself. It appears that this goes beyond making someone immortal, since it is shown in the prequel manga that he can age and rejuvenate in a matter of days depending on the state and prosperity of Saga. This process also alters Jofuku physically and mentally to the point of leaving him incapacitated for the rest of the manga.

Powers

 * Immortality—Something to highlight about the functioning of immortality is that it seems that the subject depends totally on the very concept of Saga. Even if Saga physically disappears from the map like in 1876, Saga will somehow be inside the heart and will not be forgotten from people's memories. Although it has been shown what would happen if Saga disappears, it is unknown what would happen in the opposite case, with Saga becoming known throughout the world.
 * Rejuvenation and aging—This seems to be a side effect of the elixir; since it is linked to Saga's level of prosperity and collective memory, the powers wax and wane depending on the state of the prefecture.

Trivia

 * The name “Furofuki” is said to come from the word “Furofushi”, which means “do not grow old, do not die” in Japanese.
 * In October 2008, the Saga-Xu Fu International Symposium was held in the city of Saga. Many researchers from Japan, China, Taiwan, and South Korea participated and made presentations. A lecture was also given on the relationship with the Yoshinogari site.