He is voiced by Yuki Kaiji in the Japanese version of the anime and Brian Beacock in the English version.
Walker wears a sweatshirt and is almost always seen carrying his backpack full of manga. He is half-Japanese, and his light-colored hair might be natural. His typically wears an expression of a wide smile with closed eyes, known in Japanese film and literature as "kitsune no me" (fox eyes), which is applied to characters who are sly and mischievous. He and Erika were asked to remain in their group's van during the invasion of the Yellow Scarves' hideout because they would "stand out too much."
Walker is a mysterious person. His expression gives him a carefree, clueless air, and his frequent talk of manga, understood only by Erika, gives others the impression that he is a delusional fanatic. It has been stated by Erika and himself several times that they can no longer see the difference between reality and fiction.
Despite the impression others have of him, Walker is a serious thinker and is quick to take action for people and causes that are important to him. He and Erika were members of the Blue Squares and are currently members of the Dollars, but their loyalty is to Kyouhei. Remnants of Walker's past exist in his actions; his favourite method of torture is letting his victim choose a light novel or manga and carrying out the contents on them in the most painful way possible.
While still unfazed by violence and quick to offer to torture their enemies, Walker is somewhat reformed since being pulled out of the underworld by Kyouhei. His refusal to live a quiet life led to his joining the Dollars.