Shunack manifests himself as a tall, muscular man with silver hair, indicating he has been enhanced by the Forest. He wears the red armor of the militaristic nation of Ragna, and totes four Rabans—All-purpose devices from Earth's past whose uses include Identification System and Cell Phone—around his bare right arm. He is often accompanied by Jessica, a colonel in the Ragna Army whose assignment is to monitor him.
About 300 years ago before the start of the story, Shunack was an assistant to the biologist Dr. Sakul. Together, they conducted experiments on the surface of the Moon in an attempt to produce trees that would thrive in harsh environments such as deserts. However, Shunack was impatient, and he decided to overstimulate the trees' genetic code, leading the trees to obtain intelligence equal to that of humans and attack the Earth, rupturing the moon in half in the process. Dr. Sakul tried to stop the trees from taking over Earth using an Environmental Defragmentation System known as E.S.T.O.C., but it was too late. Shunack, as well as Dr. Sakul's daughter Toola, were put into stay-field hibernation, to be awoken when the time was right.
Five years before the start of the story, Shunack was awoken (prseumably by the Ragna Army) to find the Earth in ruins, much of it covered by a sentient sea of trees known as The Forest. Unable to let go of the Past and the glory that civilization once was, he set out to find E.S.T.O.C. and restore the Earth to its former glory by destroying the Forest. Joining the Ragna Army, he told them all about E.S.T.O.C. and its capability to be used as an ultimate weapon. The army funded Shunack's search for E.S.T.O.C., provided that he be monitored by the Colonel Jessica.
Somewhere along the way, he decided to become Enhanced by the Forest (resulting in his silver hair) to aid in his search for E.S.T.O.C.
Shunack searched for E.S.T.O.C., and eventually found it, but he could not use it without the Raban owned by Dr. Sakul's daughter, Toola, which contained the Genetic Password to activate the Environmental Defragmentation System. After Five Years, and at the beginning of the story, Shunack heard rumors that another had been found who had awoken from stay-field hibernation. He captured Toola from the boy who was to take care of her, Agito, and convinced her that together they could return the Earth to normal.
Toola agreed with Shunack and defied Agito, until Shunack told her what E.S.T.O.C. was - a weapon of ultimate destruction. According to her Father, in order to restore Earth to its former glory, it must first be 'reduced to ashen rock'. Toola attempted to commit suicide to stop Shunack from fulfilling his plan, but he stopped her.
Agito eventually came and rescued Toola, defeating Shunack by absorbing him completely into the Forest. Once Shunack became one with the Forest, he redeemed himself by realizing how mankind and the Forest can live in Harmony.
- It is possible that Shunack was inspired by the main antagonist of Final Fantasy VII, Sephiroth. Several similarities exist between the two villains:
- Both have silver hair (Though in Shunack's case it is more pertinent to the story).
- Both have messianic complexes.
- Both think that they are the good guy, and that they are doing what is best for their planet.
- Both are confident and sadistic, and take pleasure in doing harm to others when it suits their purposes.
- Both Shunack and Sephiroth share genetic similarities with the Hero (Sephiroth and Cloud both have been injected with the cells of Jenova; Shunack and Agito both have been Enhanced by the Forest)