Deasta is a forward and the captain of the team known as Makai Gundan Z, also referred to as Hell Army Z, and later becomes a key member of the combined team Dark Angel. His background is tied to a demonic legend; he is presented as an ancient demonic being who appears once every thousand years to carry out a ritual. This ritual involves kidnapping a human to serve as a sacrifice with the goal of awakening a Demon Lord, a mission that defines his primary motivation. He hails from a dark realm called Demon's Gate, a location that serves as his team's base.

Physically, Deasta has a distinctive appearance designed to reflect his otherworldly nature. He has long, auburn hair and slightly tanned skin. His most notable feature is his light forest green eyes, which are characterized by two long upper lashes on each eye. His personality is consistently portrayed as cruel, ruthless, and arrogant. As the leader of a demonic team, he is aggressive and often threatens his opponents, frequently taunting them by claiming he will eat their souls. He possesses a very strong loyalty to the Demon King he serves, and his arrogance and overconfidence in his own abilities are presented as his primary weaknesses.

In the story, Deasta plays the role of an antagonist. His first appearance is in a cameo, but he becomes directly involved when he arrives at Inazuma Japan's training ground to abduct Haruna Otonashi, identifying her as the chosen sacrifice for the Demon Lord. This kidnapping creates a major conflict, forcing the main characters to split into two groups to rescue their friends. The group led by Kidou Yuuto goes to Demon's Gate to confront Deasta directly and save Haruna. He escalates the conflict by engaging this group in a soccer match, with the fate of Haruna serving as the wager.

Key relationships define his role in the plot. His primary adversary is Kidou Yuuto, whose sister he has kidnapped. He also has a rivalry with Sein, the leader of the angelic team Tenkuu no Shito, who kidnaps another character for a similar purpose. This rivalry is so central that the two enemies are later forced to merge their teams, combining Makai Gundan Z and Tenkuu no Shito to form a single, more powerful team called Dark Angel, with Deasta as its captain. It is later explained that Deasta and half of his original team were under a hypnotic spell from a stone that compelled them to form this alliance. Once the spell wears off, his true loyalty returns to his original mission of resurrecting his master.

Throughout his arc, Deasta shows little to no development or change of heart. Even after being defeated by Kidou's team, he does not abandon his purpose. Instead, he and his original team flee with the stated intention of waiting another millennium for the chance to once again try to awaken their Demon Lord, suggesting a cyclical nature to his existence.

As a player, Deasta is a powerful forward known for his offensive hissatsu techniques. His notable abilities include Black Thunder, a tactic that allows him to speed past opponents and freeze them in place, and Dark Matter, a powerful shooting technique he uses to score goals. His strength is demonstrated when he quickly scores two goals against the main characters at the start of their match, showcasing his team's monstrous power and immediately putting his opponents at a disadvantage.