Jack Wallside, known in Japan as Heigorou Kabeyama, is a defender who appears in the Inazuma Eleven: Ares no Tenbin anime. In this series, his role is significantly different from his prominent position as a starter in the original Raimon team. In Ares no Tenbin, Jack Wallside attends Rampart Junior High. However, he does not play in the match against Raimon because he is sidelined with an injury, acting only as a support member for his team during that time.

In terms of background, Jack is characterized by his large, imposing stature, which makes him a natural fit for a defensive position. His physical mass is a key asset, allowing him to act as a formidable obstacle for opposing forwards. Despite his size, his most defining personality trait across his appearances is a significant lack of confidence. He is known to be shy and cowardly, often becoming fearful before important matches. This timidity is sometimes so overwhelming that he looks for ways to avoid playing, such as making excuses to go to the bathroom.

His behavior is also influenced by a desire to impress others, particularly his younger brother, Zak Wallside, who looks up to him. This desire can push him to confront his fears, such as his well-documented acrophobia, or fear of heights, which he has struggled to overcome when attempting certain techniques. In the original continuity, Jack held deep respect for his captain, Mark Evans, who often helped him find the courage to play. This foundational relationship that defines his character development in other story arcs is not a focus in the Ares timeline, where his participation is limited due to injury. His notable abilities are centered on defense, with techniques like The Wall and The Mountain that emphasize his role as a immovable object on the field.