Hideyoshi Soya, also known by the alias Tricky, is a supporting character introduced during the team tournament arc of the series. He is a thirteen-year-old boy with a distinctive appearance, featuring orange and brown hair and gray eyes. His birthday is May 5th. Hideyoshi is first encountered by the protagonist Kosuke Ueki and another power user named Ai Mori when they seek a fifth member for their team.

At his core, Hideyoshi is a deceptive and cunning individual who prefers trickery and unorthodox tactics over direct, head-on confrontation. In battle, he is known for employing an array of novelty gags and pranks, such as soy sauce bombs, to disorient and outmaneuver his opponents. While he can sometimes appear cowardly or weak, especially when his tricks fail, he becomes a formidable foe when his sneak attacks are executed effectively in conjunction with his unique power. Despite his tricky nature, he has a strong sense of loyalty and responsibility, particularly towards a group of orphaned children he looks after at a place called the Sun House. This caring side of his personality is a major driver for his actions throughout the story.

Hideyoshi's primary motivation stems from his connection to the Sun House and his first Celestial King Candidate, a kind-hearted heavenly being named Nero. Nero did not desire to become the King of the Celestial World; instead, he wished to use his time on Earth to help humans, specifically by caring for the children at the Sun House. Hideyoshi, wanting Nero to be able to stay on Earth longer, willingly offered to become a power user. However, during a fight, Nero broke the rules to help Hideyoshi and was subsequently sent to Hell as punishment. This event leaves Hideyoshi with a deep sense of regret and a powerful desire to rescue Nero. After Nero's fall, Hideyoshi is assigned a new Celestial King Candidate named Zack. He despises Zack, who is cruel and self-serving, in stark contrast to Nero. Zack pressures Hideyoshi to join a team of nasty power users he is assembling. Hideyoshi refuses this offer, which puts the Sun House and the children he protects in danger.

Hideyoshi's role in the story solidifies when he agrees to join Ueki's team. He is motivated by the opportunity to save Nero, learning that Ueki and his friends might be able to help him achieve this goal. Within the team, his deceptive combat style and unique ability serve as valuable assets, allowing the group to overcome various challenges. His relationship with his teammates is somewhat ambivalent; at the end of the series, Ai Mori refers to him as the useless member of the team, though in the anime adaptation, she also calls him the secret savior for a critical act of support he provides to Ueki. This suggests a development from being a reluctant, trickster ally to a trusted, if unconventional, comrade who plays a pivotal role when it matters most.

Hideyoshi possesses a noteworthy ability that complements his deceptive personality. He has the power to turn voices into portraits. By using this ability, he can create a portrait from which the recorded voice will later emanate. The condition to activate this power is that he must bend his fingers or his toes. He can use his own voice or capture the voices of his opponents, making his tactics highly unpredictable. For instance, during a fight with Team Marilyn, he placed his portraits on a teammate's towels, then triggered the voices to launch a powerful sonic attack. This power, combined with his arsenal of practical jokes and trick items, makes him a master of battlefield deception and surprise attacks, perfectly embodying his nickname, Tricky.