The character known as Ivan, also referred to in some sources as Avan, is a pivotal figure within the narrative of Dragon Quest: Dai no Daibōken. He is established as a legendary hero from a past era, celebrated for having once defeated the Dark Lord Hador. Following this great victory, he dedicated his life to training a new generation of warriors and mages to protect the world from future threats.

Ivan is typically depicted as a tall man with distinctive grayish-blue hair styled in large curls. He often wears a red uniform with epaulettes and is seen with glasses, though he does not require them for vision. His personality is multifaceted; while he is an exceptionally skilled and serious hero when a situation demands it, he is also known for being a very kind, extravagant, and good-natured person. As a teacher, he is demanding and imposes a severe training regimen on his students, but this strictness stems from a genuine desire to see them surpass their limits. He holds a deep affection for those he teaches, considering their growth and success to be of paramount importance. One of his more unexpected hobbies is cooking.

Ivan's primary role in the story is that of a mentor to the young protagonist, Fly. At the beginning of the adventure, he arrives on the island of Dremline, where Fly lives, accompanied by his disciple Pope, a young magician. His purpose is to assess Fly's potential and train him to become a great hero, as he recognizes an innate and powerful force within the boy, symbolized by a dragon mark that appears on Fly's forehead in moments of duress. He creates a protective dome around the island to shield the peaceful monsters there from the growing influence of the resurrected Dark Lord, Hador, allowing him to conduct Fly's training in relative safety.

His relationship with his students is the most significant driver of his actions. He is the master of Pope, who specializes in magic, and also instructs Sam, another student who wields a magical gun. His training with Fly is intense but tragically cut short. Hador, now more powerful than ever and serving an even greater evil, breaches Ivan's defenses and attacks the island. In a desperate battle to protect his students and the world, Ivan confronts the formidable Hador. Ultimately, he makes the ultimate sacrifice, using a powerful self-sacrificial attack that severely wounds Hador but costs Ivan his own life. This defining moment serves as the catalyst for Fly and Pope to embark on their quest, driven by a desire to honor their master's memory and defeat the forces of darkness he gave his life to oppose.

In terms of abilities, Ivan is a legendary hero of immense power. Even retired from active heroics, his prowess is demonstrated when he single-handedly erects a massive magical barrier to protect the entire island of Dremline from the demonic influence of the Dark Lord. As a master warrior and sage, his physical combat skills are unparalleled, and he is knowledgeable in both offensive and defensive magic. One of his most notable techniques is a powerful sacrificial spell, which he uses in his final confrontation with Hador. This technique is potent enough to grievously wound the resurrected Devil King, a feat that underscores the heights of his power from his prime as the world's savior.