The Hero Runner Replicas are Shoes in Splatoon. They cannot be purchased, but rather earned by beating the Hero Mode.
The Hero Runner Replicas appear the same as they do in the main story, being black shoes with lime green outcroppings on either side. They have a black strap and green trim, but the blue spots do not have a trailing effect like they do in Octo Valley. The shoes do not change color based on the player's ink.