Iwanoi, known as Spyke in English adaptations, is a recurring character in the Medabots franchise. He is a male student who appears to be around ten years old and is a consistent member of the group known as The Screws.

His personality is largely defined by his position within The Screws, to which he is fiercely loyal. He habitually addresses his leader with great deference and is prone to panic and cowardice when faced with difficult situations, often crying out for help. Despite his timid nature and frequent failures, he is deeply devoted to his leader's schemes and strives to please her, even though his efforts usually end in defeat. This loyalty is a core part of his character, extending beyond his human associates to his Medabot partner.

In the original video games, Iwanoi is depicted as being skilled in informatics and programming, taking pride in his reputation as a hacker. This technical aptitude is demonstrated in his actions during certain game plots, such as when he assists by disabling electronic locks. However, this aspect of his character is less prominent in the anime adaptation, where his technical knowledge is not heavily featured.

A central characteristic of Iwanoi, particularly in the anime, is his status as one of the worst Medafighters. This poor performance is attributed to a specific technical issue: his primary Medabot, Cyandog, is equipped with a Monkey Medal. The Monkey Medal is designed for close combat, but it is placed in a DOG-type body that is built for shooting attacks. This incompatibility severely hinders his chances of winning Robattles. Rather than solve the problem by switching to a compatible Medal, Iwanoi refuses to abandon his original partner. His solution is to upgrade to a newer dog-type body, Krosserdog, while keeping the same incompatible Monkey Medal, prioritizing his bond with his Medabot over tactical advantage.

His abilities and development differ between the series and the games. In the original anime, he is portrayed as almost entirely incompetent in battle, leading to him being temporarily expelled from The Screws on two occasions due to his losing streak. In the sequel series, Medarot Damashii, his combat skills show marked improvement over these earlier portrayals. He achieves training victories against fellow Screws members and performs competently in major battles, demonstrating heightened competence.

Iwanoi's role in the story is consistently tied to his membership in The Screws. He is frequently involved in their antics and schemes against the protagonist, though the group sometimes joins forces with the main characters when the situation demands it. His key relationship is with his leader, whom he serves without question. His struggles and victories also directly influence other characters; for instance, his repeated defeats of another member motivate that character's Medabot to run away. Over the course of the franchise, he has used several Medabots including Bluesdog, Cyandog, Purple Collar, Danin, and Straywolf.