Heidayu is a recurring character who first appeared in The Legend of the Ninja Hero!.
Heidayu is a follower of Kagetomo and works as the leader of his subordinates. Years prior, Kagetomo was next in line to be the chief of Ninja Village, but Chief Hanzo would later refuse Kagetomo the position, claiming that Kagetomo was not worthy of the role due to his thirst for ambition. Kagetomo left the village, swearing revenge; Heidayu joined Kagetomo as his dedicated follower. In the years that followed Kagetomo formed an army of ninjas dedicated to his cause.
During Kagetomo's attack on the village, Heidayu's role was to delay pursuers after Kagetomo kidnapped Hanzo. Kagetomo was able to hold back Ash and Sanpei in a battle with no clear winner, retreating once he was certain that his objective had been fulfilled. Later, he battled Ash and Sanpei again during the villagers' attempt to rescue Hanzo, but was defeated after Ash's Frogadier evolved into Greninja. Following Kagetomo's defeat and reform, Heidayu left Ninja Village with his friend on another journey.