The elixir is located In a palace called Hōrai where both the Tensen and the Dōshi reside. There are a total of 8 Tensen, a other only 7 of them reside in Hōrai, the 8th was banished and wanders the island, she is also an enemy to the other Tensen. The Tensen are humanoid beings created from humans and flower Tao, in any case they are not human, they posses incredible regenerative abilities and the only way to kill them would be to completely destroy their tanden, with an opposite Tao attribute.