Origin: Spirits of the Past

Their reckless race to the water hole at the bottom of Neutral City disrupted the fragile peace between the humans and the Forest. The disturbance awakened the ire of the Druids, the tree-like beings who control the water supply. This incident fractured Agito's friend group and directly led to Agito becoming separated from Cain and Minka, setting in motion the chain of events where he discovered the cryogenic machine and revived Toola.

E.S.T.O.C. stands for Environmental Subsystem Tactical Operations Console, a colossal mechanism built into a volcano by Dr. Sakul, Toola's father. It was designed as an environmental safeguard to protect humanity from the altered Forest's changes. Both the Forest and Ragna wanted to control it for opposite reasons, the Forest feared its destruction would upset the balance, while Shunack and Ragna wanted to activate it to restore Earth to a pre-Forest state, even if it meant devastating consequences.

Shunack was a Ragna soldier who had undergone genetic enhancement by the Forest, giving him extraordinary power but also binding him to the trees. Despite being enhanced by the Forest, he harbored deep resentment toward it and wanted to use E.S.T.O.C. to restore Earth to its pre-Forest state, essentially destroying the sentient trees and reclaiming the planet for humanity, even if that meant massive destruction.

Agito underwent enhancement for two reasons. First, his father Agashi had already become nearly tree-like after years of using dangerous enhancements, and Agito faced the same fate. Second, with Shunack threatening to activate E.S.T.O.C. and destroy the world, Agito needed the Forest's power to stop him. The enhancement turned his hair silver, granting him a direct connection to the Forest and the strength to confront Shunack.

During his duel with Shunack at E.S.T.O.C., Agito merged with the Forest, becoming a living conduit of wood and will. This transformation allowed him to absorb Shunack, the enhanced soldier who had been fighting against the Forest. Through this merger, Agito gained the power to stop Shunack's plans and became the bridge between humanity and the trees.

The relationship is reciprocal. The genetic exchange works both ways, humans who undergo enhancement gain remarkable strength but also tend to become tree-like over time. Conversely, the Forest itself is altered by human life and produces new humans within enormous fruit. This bond means neither can exist without the other, and the Forest revealed this truth to Agito on another plane after his transformation.

The Raban was a portable communication device that represented Toola's connection to the old world and her role as a link to the technology of the past. By discarding it, Toola symbolically severed her ties to the conflict between Ragna and the Forest. She chose to live in harmony within the Forest rather than remain separate from it, embracing a new future where humans and trees coexist peacefully.

Agashi, Agito's father, had been using dangerous genetic enhancements for years to gain powers similar to what the Forest provides. This gradually transformed him into a near-plantlike state, his body becoming more tree than human. His transformation served as a warning to Agito about the cost of using such enhancements, though ultimately Agito had to make the same desperate choice to save himself and the world.

Toola was placed in a cryogenic pod inside a colossal machine in Neutral City centuries earlier, around the time the genetically engineered trees first arrived on Earth. She slept through the entire period when the Forest rose to power, the ecocide occurred, and humanity's world was transformed. Her Raban and the machine were preserved in a forbidden sanctuary where Agito accidentally revived her.

The Forest deployed towering plant guardians to protect itself and maintain the delicate balance it had established with humanity. When the Forest sensed danger from Shunack's approach toward Toola, fearing he could use her Raban to locate and destroy E.S.T.O.C., it created a massive plant guardian to block their meeting. These guardians represent the Forest's ability to actively defend itself against threats to the ecological balance it controls.

Dr. Sakul, Toola's father, discovered that his own early genetic research on the trees had inadvertently created both the sentient Forest and E.S.T.O.C. His work spawned a new world order where trees became intelligent and dominant, while simultaneously creating the safeguard (E.S.T.O.C.) meant to protect humanity from those very changes. This revelation showed that he was responsible for both the problem and the attempted solution.

Neutral City is a settlement carved from shattered skyscrapers at the Forest's edge in post-apocalyptic Japan. It exists as a fragile compromise where humans can live under the Forest's rule. The Druids control the water supply for both trees and humans, forcing humanity into a tense coexistence with the sentient Forest. The city's name reflects its role as a neutral zone between human settlement and Forest territory.