Chapter 18 of Hell's Paradise: Jigokuraku.
The tree man says that he can tell them about the elixir and guide them to the village but Yuzuriha believes that its a trap. After persuading Yuzuriha by mentioning the village has a bath, the group follows him to the village. Sagiri questioned whether they should trust him. Gabimaru wanted to take his chances as long as he knows about the elixir but also tells her that if the tree man seems suspicious he will take it down. The tree man tells them that it will not trick them and the monster and butterflies will not come near the village. He also reveals that the monsters are called the Sōshin, guardians of the island. They arrive at the village and entered the tree mans house. While Yuzuriha and Sagiri take a bath, Gabimaru and Senta talk to the tree man about the elixir. The tree man indicates that the elixir indeed exists on the island revealed to be known as Kotaku. The tree man gives a lay out of the island and tells them that the elixir, also known as Tan, is located at the center of the island called Hōrai. He also tells them that soon they will meet Lord Tensen, a perfect immortal being and will meet their demise. Later, Chōbē and Tōma are defeated by the mystery man.