The Banko is meant to cultivate a greater quantity of Tan than the pit in Eishū, however, because the Banko's Tao overwhelmingly consumes the humans forming beneath it, the flower constantly wilts away and will need another century to be reborn again. According to Mei and Rien, the Banko drops during the night, which in turn causes the Tensens' Tao to become weakened, but goes into full bloom after morning. The Banko also possesses all of the Five Elements.
Upon fusing with Zhu Jin, the Banko became powerful enough to take over Hōrai as if the palace became its entire body. As a result, anything living within it will undergo Arborification from either the Tan particles in the air, its roots, or the giant monsters created.
At some point, Rien used the humans that traveled to Kotaku to create the Banko in his laboratory in hoping that he could create more of the Tan elixir. However, due to its high demand of needing more high quality Tao to stay alive, Rien concluded that the Banko was not yet perfect. Over the years, Rien tried to keep the Banko from dying but is met with failure with each attempt and had to wait for centuries for it to bloom once more. Rien also discovered that the Tan from the Banko became to potent for even the Tensens to consume and its effects would disrupt the balance in their Tao. In order to have the flower remain alive and produce more of the needed perfected elixir, Rien developed a plan to turn the human race into Waitanhua flowers and have them connect with the Banko.
During the Edo period, upon the arrival of a troublesome group of humans, Rien encountered Aza Chōbē whose Tao was looked at as being the key to completing his research. Once Rien was finished with his experimentations on him, he was finally able to create the Elixir of Life and was ready to put his plan into motion. However, after the humans invaded Hōrai to retrieve the elixir and escape the island, Zhu Jin received critical damage to their body by Yamada Asaemon Shion and crawled their way to the Main Temple to merge with the Banko. The Banko emerges out of the Main Temple with Zhu Jin fused and takes over Hōrai.
- The Banko bears reference to certain religious and mythological elements:
- The name "Banko" translates to "Pangu" (盤古) in Chinese. The Banko most likely refers to the Pangu, the first living being that has been said to be the creator of all in Chinese mythology.
- The fact that it feeds off of human lives to stay alive is akin to Jubokko, a yōkai tree in Japanese mythology that grows by feeding on human blood.
- Rien forbidding Zhu Jin's past consideration of consuming the Banko is akin to the story of the Tree of the knowledge of good and evil in Abrahamic religions, in which Adam and Eve, the first humans, ate the forbidden fruit produced by the tree despite being told otherwise.
- The Banko creating Tan to extend lives is similar to the special tree, the Ginsengfruit tree, of Immortal Zhenyuan in Journey to the West, which produces only 30 pieces of fruit every 9,000 years; the fruit is shaped like an infant less than three days old. A person who smells the fruit can extend his lifespan by 360 years, while a person who eats the fruit can live for another 47,000 years.
- The Banko is the only known living thing to have all of the Five Elements.
- ↑ Jigokuraku Chapter 61, page 16