Gaku Ishikawa is a supporting character in the soccer-themed comedy. His background is established as a third-year student at Fujimi High School, where he serves as the captain of the school's soccer club. On the field, he plays as a midfielder and wears the jersey number 6. He is known for being the only member of the soccer team who has a girlfriend, a girl named Yuri Tamura. A noteworthy aspect of his personal life is that his girlfriend becomes a devoted fan of the team's star player, Aoyama. As a result of her enthusiasm, Ishikawa also ends up joining Aoyama's official fan club.

In terms of personality, Ishikawa is characterized by a supportive and perhaps slightly impressionable nature, as his decision to join the fan club is directly influenced by his girlfriend's interests. His role in the story is that of a reliable upperclassman and leader of the team. As captain, he maintains the responsibilities that come with the position, managing his teammates and contributing to the club's dynamic. He is not an eccentric character like many of his peers but rather serves as one of the more grounded members of the team, even as he participates in their admiration for Aoyama.

His key relationships are primarily with his girlfriend, Yuri Tamura, and with his teammates on the Fujimi High School soccer club, most notably Aoyama. While he does not undergo a dramatic character arc, his development is shown through his steady presence and his unique position as a captain who is also an admitted fan of one of his own players. This dynamic highlights the team's overall respectful, if unusual, admiration for Aoyama's talent. In terms of notable abilities, Ishikawa is a capable and accomplished soccer player, skilled enough to hold the position of team captain and play as a midfielder, a role that requires both offensive and defensive skills. His birthday is September 15.