Zack Kuwabara is a supporting character in the series 'Kamen Rider Gaim.' He is the user of the Kamen Rider Knuckle transformation, utilizing the Kurumi Lockseed. Zack starts as a member of Team Baron, one of the street dance crews involved in the Inves Game. Over time, he becomes a loyal friend and trusted ally, often acting as a mediator within his group. Zack’s sense of justice and strong moral compass make him a key figure in the fight against the series’ antagonists.